Add c++20 character types

[i-garrison]

This change adds char8_t character type from c++20

[jonahgraham]

The build on this is failing, best guess is some inlined constant or change of used internals from cdt core has changed causing the failure:

Error:  Failed to execute goal org.eclipse.tycho:tycho-p2-plugin:3.0.3:p2-metadata (baselinereplace-p2-metadata) on project org.eclipse.cdt.ui: baseline and build artifacts have same version but different contents
Error:     no-classifier: different
Error:        org/eclipse/cdt/internal/ui/refactoring/rename/ASTManager.class: different
Error:  -> [Help 1]

It would be nice to know why it has changed, but either way, the version of org.eclipse.cdt.ui needs to be bumped.

[i-garrison]

org.eclipse.cdt.ui needs to be bumped.

Hi @jonahgraham either I bumped the wrong piece in 4411c45 or it did not helped here.

[jonahgraham]

Weird goingson now. The current code passes code cleanliness without the bump, so not sure what is going on and I won't spend much time on that. I will review this later.

[i-garrison]

Well there actually was a bump in Navigator cleanup 47275c3
I just did a rebase onto main and tests are now passing.

[jonahgraham]

Thanks for figuring out what happened.

[jonahgraham]

This LGTM. All the changes made seem good. There is still the possibility that some other areas need modification, but I don't have the knowledge to know what may be missing here.

I will make the small change mentioned and submit today for M1.