build: CMake refactoring and fixes

Includes:
- fix int64x64 parsing order, remove cached entries in macros-and-definitions and in the docs
- update launch.json scratch names
- add a ctest entry per executable
- forward POSIX signal in ns3 (to get segmentation fault)
- prioritize Ninja generator instead of Makefiles
- add tests for unused utils source files
- remove dummy file and add tests to check for unused source files
- add missing examples and clean up unnecessary definitions
- missing feature entry for LTE used by pybindgen
- refactor CMake related filenames
- fix python libraries and include directories bindings
- fix brite example name
- Keep C++ compiler and flags when refreshing
- Disable precompiled headers when Ccache is found
- Mark find_external_library headers as advanced
- consolidate auxiliary files: build-status.py, _cache.py and .lock-waf_sys.platform_build files are merged into .lock-ns3_sys.platform_build
- scan .cc sources used in bindings and update docs

doc/tutorial/source/conceptual-overview.rst

@@ -887,7 +887,7 @@ most of our *repositories* will look:
   drwxr-xr-x                               [up]
   -rwxrwxrwx  12507 nov 23 23:12 AUTHORS
   drwxrwxrwx      0 dez 30  2020 bindings
-  drwxrwxrwx   4096 nov 28 11:25 buildsupport
+  drwxrwxrwx   4096 nov 28 11:25 build-support
   -rwxrwxrwx 189870 nov 28 10:13 CHANGES.html
   -rwxrwxrwx   1490 nov 22 10:56 .clang-format
   -rwxrwxrwx   5079 nov 28 10:50 CMakeLists.txt

doc/tutorial/source/getting-started.rst

@@ -677,10 +677,10 @@ output that looks similar to the following::
 
    -- Configuring done
    -- Generating done
-   -- Build files have been written to: /mnt/dev/tools/source/ns-3-dev/cmake_cache
+   -- Build files have been written to: /mnt/dev/tools/source/ns-3-dev/cmake-cache
    Finished executing the following commands:
-   mkdir cmake_cache
-   cd cmake_cache; /usr/bin/cmake -DCMAKE_BUILD_TYPE=release -DNS3_NATIVE_OPTIMIZATIONS=ON -DNS3_EXAMPLES=ON -DNS3_TESTS=ON -G Unix Makefiles .. ; cd ..
+   mkdir cmake-cache
+   cd cmake-cache; /usr/bin/cmake -DCMAKE_BUILD_TYPE=release -DNS3_NATIVE_OPTIMIZATIONS=ON -DNS3_EXAMPLES=ON -DNS3_TESTS=ON -G Unix Makefiles .. ; cd ..
 
 
 Note the last part of the above output.  Some |ns3| options are not enabled by
@@ -1011,7 +1011,7 @@ Corresponds to
 
 .. sourcecode:: console
 
-  $ cd /ns-3-dev/cmake_cache/
+  $ cd /ns-3-dev/cmake-cache/
   $ cmake -DCMAKE_BUILD_TYPE=release -DNS3_NATIVE_OPTIMIZATIONS=ON -DNS3_ASSERT=OFF -DNS3_LOG=OFF -DNS3_TESTS=ON -DNS3_EXAMPLES=ON ..
 
 Build command
@@ -1027,7 +1027,7 @@ Which corresponds to the following commands:
 
 .. sourcecode:: console
 
-  $ cd /ns-3-dev/cmake_cache/
+  $ cd /ns-3-dev/cmake-cache/
   $ cmake --build . -j 16 --target test-runner # This command builds the test-runner target with the underlying build system
 
 
@@ -1041,7 +1041,7 @@ Which corresponds to:
 
 .. sourcecode:: console
 
-  $ cd /ns-3-dev/cmake_cache/
+  $ cd /ns-3-dev/cmake-cache/
   $ cmake --build . -j 16  # This command builds all the targets with the underlying build system
 
 Run command
@@ -1055,7 +1055,7 @@ Corresponds to:
 
 .. sourcecode:: console
 
-  $ cd /ns-3-dev/cmake_cache/
+  $ cd /ns-3-dev/cmake-cache/
   $ cmake --build . -j 16 --target test-runner # This command builds the test-runner target calling the underlying build system
   $ export PATH=$PATH:/ns-3-dev/build/:/ns-3-dev/build/lib:/ns-3-dev/build/bindings/python # export library paths
   $ export LD_LIBRARY_PATH=/ns-3-dev/build/:/ns-3-dev/build/lib:/ns-3-dev/build/bindings/python
@@ -1161,10 +1161,10 @@ system and underlying build system. https://cmake.org/cmake/help/latest/generato
 
   ...
 
-  $ -- Build files have been written to: /ns-3-dev/cmake_cache
+  $ -- Build files have been written to: /ns-3-dev/cmake-cache
 
 
-There will be a NS3.cbp file inside the cache folder used during configuration (in this case cmake_cache).
+There will be a NS3.cbp file inside the cache folder used during configuration (in this case cmake-cache).
 This is a Code::Blocks project file that can be opened by the IDE.
 
 When you first open the IDE, you will be greeted by a window asking you to select the compiler you want.
@@ -1217,11 +1217,11 @@ system and underlying build system. https://cmake.org/cmake/help/latest/generato
 
   ...
 
-  $ -- Build files have been written to: /ns-3-dev/cmake_cache
+  $ -- Build files have been written to: /ns-3-dev/cmake-cache
 
 
 There will be a NS3.xcodeproj file inside the cache folder used during configuration
-(in this case cmake_cache). This is a XCode project file that can be opened by the IDE.
+(in this case cmake-cache). This is a XCode project file that can be opened by the IDE.
 
 Loading the project will take a while, and you will be greeted with the following prompt.
 Select to automatically create the schemes.
@@ -1288,7 +1288,7 @@ executing each test, which will actually look something like:
 
   -- Configuring done
   -- Generating done
-  -- Build files have been written to: /ns-3-dev/cmake_cache
+  -- Build files have been written to: /ns-3-dev/cmake-cache
 
   ...
   Scanning dependencies of target tap-creator