Deduplicate the frameTable during compaction

[mstange]

Main branch | Deploy preview

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When we combine the per-thread frame tables from the gecko profile format into the shared frame table of the processed format, we don't do any deduplication, because deduplicating would slow down loading. But we could do it during profile compacting (after sanitization) instead. This will also make it work for profiles captured from older samply versions, or when re-uploading old shared profiles.

In the profiles linked above, if I re-upload with the "Screenshots" checkbox unchecked (so that sanitization runs profile compacting), I get the following numbers:

• Without frame table deduplication: 52.1 MB compressed, 370.4 MB uncompressed, 224210 frames
• With frame table deduplication: 51.6 MB compressed, 365.7 MB uncompressed, 132059 frames

This PR doesn't implement stack table deduplication; I expect some more savings from that, but it needs frame table deduplication first. Edit: Implemented in #6137, doesn't actually save much.

[codecov]

Codecov Report

❌ Patch coverage is 93.10345% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.52%. Comparing base (2880a96) to head (9c0b46f).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/profile-logic/profile-compacting.ts	93.10%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6017      +/-   ##
==========================================
+ Coverage   83.50%   83.52%   +0.01%     
==========================================
  Files         342      342              
  Lines       36183    36261      +78     
  Branches    10133    10141       +8     
==========================================
+ Hits        30216    30288      +72     
- Misses       5539     5545       +6     
  Partials      428      428              

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