Add a data broker launcher (issue #17)

[wowaddonmaker]

Adds a data broker launcher, as requested in #17.

Display bars that host data broker objects can now launch EasyFind, so a minimalist UI does not need the minimap button. Left-click toggles the search bar, right-click opens the options, matching the minimap button exactly. Verified in game with Titan Panel.

Notes

• Nothing is bundled. EasyFind only publishes the object; every display that shows one already embeds the library. With no such display installed the library does not exist, registration is skipped, and nothing changes.
• Registered at login rather than at load, so a display that loads after us has already created the library. Creating an object fires the library's own DataObjectCreated callback, which is how displays pick up late registrations.
• No new locale keys. The launcher tooltip reuses the existing minimap button strings.
• The minimap button and the launcher now share one icon constant instead of repeating the texture path.

Release

Version bumped to 2.1.4 (patch: additive, no behavior change for existing users). Changelog entry added. What's New content rewritten for 2.1.4 in all 11 locales, with the content gate bumped alongside it so the popup announces the launcher rather than 2.1.3's notes.

Verification: luacheck clean across 127 files, all locales compile, locale parity holds at 560 keys across 11 files, and every L[] key referenced in code is defined. Against the shipped 2.1.3 zip this is 181 files in and 181 out, none added or removed.

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Superseded before release. The v2.1.4 tag and release cut from this PR were withdrawn a few minutes after publishing and never reached CurseForge, so no one ran this build. The launcher shipped in 2.1.4 together with the follow-up fixes in #19: the launcher now toggles the search bar shut instead of reopening it, and the notes were reworded to say support was added for data broker displays rather than implying the minimap button was replaced.