[kpal81xd]

The Editor's Launch profiler is replaced by the Inspector's Performance tab (playcanvas/editor#2500), so the Profiler page goes:

• Removes optimization/profiler.md (English and Japanese), its images and its sidebar entry.
• Redirects /user-manual/optimization/profiler/ to /user-manual/optimization/inspector-performance/.
• Adds a paragraph and a screenshot of the Launch menu to Inspector Performance's "Recording the Start of the Application", on the Profiler option, which records from the start (Engine 2.23 or later). The old profiler screenshots go with its page.
• Points the links to the old page (Migrating from Unity, App Stats, Optimization, Optimizing WebXR) at Inspector Performance.

Merge after playcanvas/editor#2500 ships.

Smoke test:

1. Open /user-manual/optimization/profiler/. It redirects to Inspector Performance.
2. Open Optimization in the sidebar. Profiler is gone and Inspector Performance is listed.
3. Open Migrating from Unity and click the profiler link. It opens Inspector Performance.
4. Repeat step 1 under /ja/. It redirects to the Japanese Inspector Performance page.

I confirm I have read the contributing guidelines.