emulators/Ymir: update to 0.3.0

• Improve readability by inserting a newline between the *_DEPENDS variables, and by putting USE_GITHUB with its related variables in its own block.

• Add FEATUREFLAG option, disabled by default. This enables experimental in-development features which are not yet ready for general usage but which curious users could test in their own builds.

• Refresh patch.

Changelog: https://github.com/StrikerX3/Ymir/releases/tag/v0.3.0

PR: 294807
Event: Wiesbaden Hackathon 202604