Ensure compilers are installed

[bthomee]

This PR adds additional checks to ensure the compilers are correctly installed.

• A version check is performed to verify that the desired GCC or Clang version is present.
• Each built Docker image compile and execute an example Conan CMake project.
  • Note that due to how we configured the multi-architecture Docker action, it was challenging to perform the test as a separate job step; the test is therefore performed during the image building and the files are removed afterwards.

Several additional changes are made to (i) make the images consistent with each other, (ii) remove extraneous files, and (iii) remove packages that will be moved into the tools image(s).

This change supersedes #6.

[legleux]

How are you using these images that the entrypoint being bash is useful?

[legleux]

I had suggested this before being reminded about the SCL toolset enabling.

To me it seems like an either/or. If this works, I guess it's ok but I'm suspicious and feel like this is just what enabling the toolset does... and possibly more magic.

Now none of the other binutils are tracked and updated with this (which I'm not sure how much that really matters).

[Bronek]

This is strictly better, because coverage target will detect gcov which will now be the right version to match the compiler.

[bthomee]

If there are other binutils we need, we can follow the same process to make them globally available without SCL.

An alternative would be to edit the SHELL and ENTRYPOINT to run the SCL command, but I prefer the current approach as its behavior is more consistent with what I'd expect in an image.

[Bronek]

Someone will have to review my commits, but this aside it's great !

[bthomee]

How are you using these images that the entrypoint being bash is useful?

By not setting the entrypoint, you get what's defined in the base image, and that's not what I wanted / expected when I just did "docker run" without overriding the entrypoint. Each image did something different, one presented a non-Bash shell with a long preamble, another one just did nothing. This way the experience is consistent.

I was using the shell to manually compile the rippled binary, so having the shell set like it is now is convenient.

[bthomee]

Someone will have to review my commits, but this aside it's great !

I reviewed them - thanks!