[Enhancement] Add form changes for Solgaleo, Lunala, & Marshadow cosmetic forms

[Madmadness65]

What are the changes the user will see?

Solgaleo, Lunala, and Marshadow will be able to form change into their unique cosmetic forms via their signature moves. These are custom form change methods since the Z-Moves these forms are usually attached to are not planned to be implemented.

Why am I making these changes?

The graphics for these forms were unused, and I wanted to find a reasonable way to implement them, since these forms will not impact gameplay.

What are the changes from a developer perspective?

Added PokemonForm entries for Solgaleo and Lunala so they can use their unique sprites. Entries were added to the form changes to change form when their signature move is used, Party icons needed to be added for Radiant Sun Solgaleo and Full Moon Lunala. Existing variant palettes exist for both forms, but they do lack party icons for the variants.

Screenshots/Videos

Marshadow form changing into Zenith form

zenith.mp4

Solgaleo and Lunala form changing into Radiant Sun and Full Moon forms respectively

sun.moon.mp4

How to test the changes?

Use a Solgaleo, Lunala, or Marshadow with Sunsteel Strike, Moongeist Beam, or Spectral Thief respectively. Switch out the Pokemon to see that it reverts back to normal when recalled.

Checklist

• I'm using beta as my base branch
• There is no overlap with another PR?
• The PR is self-contained and cannot be split into smaller PRs?
• Have I provided a clear explanation of the changes?
• Have I tested the changes manually?
• Are all unit tests still passing? (npm run test)
  - [ ] Have I created new automated tests (npm run create-test) or updated existing tests related to the PR's changes?
• Have I provided screenshots/videos of the changes (if applicable)?
  - [ ] Have I made sure that any UI change works for both UI themes (default and legacy)?

Are there any localization additions or changes? If so:

• Has a locales PR been created on the locales repo?
  • If so, please leave a link to it here: Add entries for Cosmog line forms pokerogue-locales#127
• Has the translation team been contacted for proofreading/translation?

[DayKev]

:wynautshrug:

Should wait until variants are also implemented

[Wlowscha]

As discussed here, this should wait until all three new forms also have variants made. Posting this so that no one else merges by mistake as I was about to do.

[SirzBenjie]

As discussed here, this should wait until all three new forms also have variants made. Posting this so that no one else merges by mistake as I was about to do.

Can we get an issue tracker for this if there isn't already one?

[Unicornpowerstar]

As discussed here, this should wait until all three new forms also have variants made. Posting this so that no one else merges by mistake as I was about to do.

Issue Momo isnt on the Discord anymore unless another artist tackle this it wont be done.