Hide palette selector for deckskins/collabs that have only a single palette

[VivianGiacobbi]

• Hides palette selector when a deckskin has one palette
• Makes the palette selector smaller both for visual flair and to reduce negative space when it's not visible.
• Replaces lovely patches that completely rewrote G.UIDEF.custom_deck_tab with an override

Additional Info:

• I didn't modify api's or I've made a PR to the wiki repo.
• I didn't modify api's or I've updated lsp definitions.
• I didn't make new lovely files or all new lovely files have appropriate priority.