CMake: Add DART_SKIP_<dep> advanced options

[traversaro]

Add DART_SKIP_ option to permit to specify that a dependency should not used even if it is found in the system.

This is useful in package managers such as vcpkg to ensure that, for a given set of enabled features, the same version of the library is build, independently from which dependency are actually installed in the system. A mpre extended rationale is provided in gazebosim/gz-cmake#63 .

[codecov]

Codecov Report

Merging #1497 into master will not change coverage.
The diff coverage is n/a.

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  Hits        17456    17456           
  Misses      12552    12552           

[jslee02]

We had a similar discussion in #1056 that is to control which component to be built (using CMake option like DART_BUILD_<component>). In this way, we could disable the components that require the dependencies you want to skip. Do you think it would also have the same effect?

[traversaro]

We had a similar discussion in #1056 that is to control which component to be built (using CMake option like DART_BUILD_<component>). In this way, we could disable the components that require the dependencies you want to skip. Do you think it would also have the same effect?

I think that could also be used in that context.

[traversaro]

Hi @jslee02, so do you prefer that I close this PR and I open implementing what was discussed in #1056 ?

[jslee02]

@traversaro Yeah, but let me create a PR based on the discussion in #1056 as I already started it if it sounds good to you as well.

[traversaro]

Perfect, thanks!

[jslee02]

Merging this PR resolves the described issue without hurting the current build system. Will revisit to consider method discussed in #1056 if needed

[traversaro]

Thanks @jslee02 !