added handling of GrammarErrors

[WouterVisscher]

following issue #76 and the changes made in OSGeo/PROJ#4108

The ReferencingFormatTest/testParse was failing, because the warnings that were used for testing in PROJ-JNI where moved in PROJ (9.5+) to a grammarErrorList().

Regrading my first fix I simply moved the grammarErrors in the same list as the warning, fixing the failing test. But I now have kept them separated, reflecting the PROJ api (both are there).
I am aware that this probably doesn't matter functionally because as far as I'm able to tell all the messages in PROJ where moved from warnings -> grammarErrors. (but it feels less messy, keep them explicit)

The added code is mostly a duplicate of the warnings implementation
I did renamed the old test testParse() -> testParseGrammarErrors() with the intention of also adding a testParseWarnings(), but I failed to trigger such a test by:

1. not being able to find a proper test (GEOGCRS) in the OSGeo/PROJ test cases
2. and lacking the Geodetic knowledge which (missing) parameter might trigger a warning in PROJ
3. and as stated previously above, probably all the warnings are now moved to grammarErrors in these cases

[WouterVisscher]

The ubuntu:latest in the workflow is still rocking a PROJ 9.4 version
A quickfix might be switching from latest -> resolute, which has PROJ 9.7.0
Without "exploding" the github-action with additional steps for downloadin/building/installing the PROJ binaries

[desruisseaux]

A quickfix might be switching from latest -> resolute, which has PROJ 9.7.0

I suggest that you try it in this pull request, so we can see the result.

[WouterVisscher]

@desruisseaux I think if hit all the comments

[desruisseaux]

You can add an @author tag with your name in the modified files if you want.

[WouterVisscher]

I also reverted the ubuntu-resolute back to ubuntu-latest

That was me not thinking. I though the runs-on was refering to docker images but those are specific github-action images (meaning there isn't a Ubuntu 26 available, at the moment)
That does leaves the "problem" of running the workflow

Easiest is solution is waiting for github-actions to update ubuntu-latest to a ubuntu 26 version, and parking this issue as a draft in the meantime
The other extreme is modifying the action and building the proj binaries ourself...

[WouterVisscher]

You can add an @author tag with your name in the modified files if you want.

I only did some copy-paste of our work/idea
this was all you 👍🏻

[desruisseaux]

Easiest is solution is waiting for github-actions to update ubuntu-latest to a ubuntu 26 version, and parking this issue as a draft in the meantime

Fine for me. I skip the test in the meantime with a note for reminding us: a95658f