Move buff tooltip controls into Display

[andybergon]

What does this PR do?

Moves buff tooltip controls from Frames into Buffs > Display. The Tooltips dropdown uses the same modifier cog as Debuffs and shares a row with Icon Glow, removing the two empty right-hand slots. Saved values and defaults stay unchanged.

Depends on #2095. Until that prerequisite merges, this draft also contains its commit; the layout-only change is commit 9e228c92.

How was it tested?

• Lua 5.1 compilation and focused mocked checks for all modes, the shared modifier key, disabled cog, and no-key warning.
• Locale key generator completed without content changes.
• The reporter supplied live-client screenshots confirming the final Tooltips/Icon Glow row and its placement on the Buffs page. Modifier hover behavior was also confirmed in-game.

Screenshots

Before compacting the relocated controls:

After:

Checklist

• New settings default OFF (no behavior change without opt-in)
• Zero cost while disabled: no events registered, no polling, no hooks doing work, no frames built
• Cheap while enabled: event-driven (no polling, no timer-based logic, no per-frame allocations)
• No writes onto Blizzard-owned frames (weak-table pattern used); HookScript/hooksecurefunc only, never SetScript on Blizzard frames
• Tested in-game on live; no version gates or pre-Midnight APIs added

The first four items refer to the unchanged runtime behavior; this commit only reorganizes addon-owned options controls.