Added a new cmake flag to enable isolation

[adityapande-1995]

This adds a new cmake argument called "ISOLATE_TEST" to use https://github.com/adityapande-1995/linux_isolate_process for isolating a test. This would mean more tests can be run in parallel, and can speed up CI. Due to the underlying implementation using the unshare system call, this can only be used in linux.

The proposal is to add linux_isolate_process as a dependency of ament_cmake_test, so that downstream packages get it for free, and hopefully add linux_isolate_process as a core package in ROS 2.

Custom repos file : https://gist.github.com/adityapande-1995/0f05b9acf72be5fbb34e80e4342cfe26

The plan further is to add a similar pytest plugin.

[cottsay]

We should also trigger a build where the flag is inverted and unconditionally enabled so we can "see what breaks" :)

[adityapande-1995]

Build round 2, with isolation enabled and a parallel executor :

• Linux
• Linux-aarch64
• Windows

Build args : --event-handlers console_cohesion+ console_package_list+ --cmake-args -DINSTALL_EXAMPLES=OFF -DSECURITY=ON -DAPPEND_PROJECT_NAME_TO_INCLUDEDIR=ON -DISOLATE_TEST=ON
Test args : --event-handlers console_cohesion+ --retest-until-pass 2 --ctest-args -LE xfail --pytest-args -m "not xfail"

Without isolation but with a parallel executor :

Build args : --event-handlers console_cohesion+ console_package_list+ --cmake-args -DINSTALL_EXAMPLES=OFF -DSECURITY=ON -DAPPEND_PROJECT_NAME_TO_INCLUDEDIR=ON
Test args : --event-handlers console_cohesion+ --retest-until-pass 2 --ctest-args -LE xfail --pytest-args -m "not xfail"

• Linux
• Linux-aarch64
• Windows

[adityapande-1995]

TODO :

• Make a pytest plguin out of linux_isolate_process