[SofaSphFluid] Several clean in the plugin components

[epernod]

Only some cleaning in:

• Class define macro
• Data and member prefix
• Move code from header to inl or cpp files

Update several plugin demo scenes.

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This PR:

• builds with SUCCESS for all platforms on the CI.
• does not generate new warnings.
• does not generate new unit test failures.
• does not generate new scene test failures.
• does not break API compatibility.
• is more than 1 week old (or has fast-merge label).

Reviewers will merge only if all these checks are true.

[hugtalbot]

[ci-build][with-all-tests]

[epernod]

@guparan @hugtalbot could you check this plugin is compiled on the CI, I have a doubt

[hugtalbot]

@epernod you could see that in the build output (cmake) and in the compilation.
In this case, no it isn't. We need to edit the appropriate scrit on CI. @guparan is on it

[guparan]

Done, let's [ci-build][with-all-tests] again 👍