feat: Parser for jenny

[st-pasha]

Description

This PR adds ability to parse Yarn files and create a YarnProject.
Not all syntaxes are covered yet, but a significant part is, and this should be enough to get started on creating a DialogueRunner.

This PR also renames the package into jenny / flame_jenny, as discussed in #2126.

Checklist

• The title of my PR starts with a Conventional Commit prefix (fix:, feat:, docs: etc).
• I have followed the Contributor Guide when preparing my PR.
• I have updated/added tests for ALL new/updated/fixed functionality.
• [-] I have updated/added relevant documentation in docs and added dartdoc comments with ///.
• [-] I have updated/added relevant examples in examples or docs.

Breaking Change?

• [-] Yes, this PR is a breaking change.
• No, this PR is not a breaking change.

Related Issues

[spydon]

Very cool, it's like its own little programming language

[spydon]

When having a look at this again, it seems like most of this code would be awesome as a separate package, since almost nothing so far seem specific to Flame, and then have the bridge package using that package (same structure as radiance will have once we get flame_radiance). Any reason that you put everything in here?

[st-pasha]

The functionality works in stages: first we load the data from .yarn files and create an internal representation; then we use that representation in order to run the dialogue in a Flame game. The second part I'm still working on atm.