Add meson option to disable explicit EC keys tests

[Mulling]

Description

This PR adds a meson option to disable explicit EC keys tests.

Checklist

• Code modified for feature
• Test suite updated with functionality tests
• Test suite updated with negative tests
• Documentation updated

Reviewer's checklist:

• Any issues marked for closing are addressed
• There is a test suite reasonably covering new functionality or modifications
• This feature/change has adequate documentation added
• Code conform to coding style that today cannot yet be enforced via the check style test
• Commits have short titles and sensible commit messages
• Coverity Scan has run if needed (code PR) and no new defects were found

[Jakuje]

Should we make it the other way round and disable the explicit curves by default and enable them only if some configuration option is provided instead?

[Mulling]

Would be better, I think debian is the only one that allows it.

[Mulling]

@Jakuje Not sure how you want to handle the workflow config, I just copied what was already done for preload_libasan.

[Jakuje]

just one nit, otherwise looks good!

[Jakuje]

lgtm. Thank you for your contribution!

[simo5]

@Mulling can you please squash the commits and rebase on main?

[Mulling]

Not sure why Coverity Scan is failing.

[simo5]

Not sure why Coverity Scan is failing.

Don't worry about it, we'll handle it later, it is just telling that actual code has changed and a scan should be rerun (it is not automatically run for "reasons").

[simo5]

LGTM