[api-minor] Replace the CMapReaderFactory, StandardFontDataFactory, and WasmFactory API options with a single factory/option

[Snuffleupagus]

• [api-minor] Replace the CMapReaderFactory, StandardFontDataFactory, and WasmFactory API options with a single
  factory/option

  Currently we have no less than three different, but very similar, factories for reading built-in CMap files, standard font files, and wasm files on the main-thread.[1]
  These factories were added at different points in time, since I cannot imagine that we'd add essentially three copies of the same code otherwise.

  Nowadays these factories are often not even used[2], since worker-thread fetching is used whenever possible to improve performance. In particular, they will only be used when either:

  • The PDF.js library runs in Node.js environments.
  • The user manually sets useWorkerFetch = false when calling getDocument.
  • The user provides custom CMapReaderFactory, StandardFontDataFactory, and/or WasmFactory instances when calling getDocument.

  Thanks to the use of import maps the impact of these separate factories on the total bundle-size is mostly avoided in the Firefox PDF Viewer, however there's still some amount of effectively dead code present there.
  In order to reduce the number of getDocument options a little bit, this patch replaces the existing options with a single new BinaryDataFactory option instead.

  A question is obviously if the option of providing custom factories to replace the default ones is actually utilized[3], by third-party PDF.js users, however that's impossible to know and outright removing the API option is probably too risky?

  Please note: Any existing third-party code using the old factories should still work[4], since we (for now) fallback to use those if provided.

  ---

  [1] Any new functionality could easily lead to more such factories being added in the future, which wouldn't be great.

  [2] Note that the Firefox PDF Viewer will never use these factories, since it "forcibly" sets useWorkerFetch = true during building.

  [3] Originally I recall that we only provided browser versions of these factories, and thus Node.js users needed to implement custom ones. However, this hasn't been the case for many years.

  [4] Barring any bugs in the patch, of course.

• Remove explicit name/filename validation in various BaseBinaryDataFactory methods

  Given that the BaseBinaryDataFactory class is only used from the "FetchBinaryData" message handler, the name/filename parameters should never actually be missing here.
  Besides, a missing name/filename would result in a "nonsense" URL and the actual data fetching would then fail instead. Hence it just doesn't seem necessary to keep this extra bit of validation now.

• Simplify the main-thread reading of "raw" built-in CMap files

  It's not entirely clear to me why we need to special-case reading of these, given that:

  • The bcmap format has been used for over a decade now, see PR CMaps binary packing #4470.
  • The bcmap files have not been updated even once, since their introduction.
  • The "raw" CMap files only contain regular ASCII characters.
  • Fetching the bytes-data directly should just work, which I've confirmed by successfully testing this patch with test/pdfs/mao.pdf and the "raw" CMap files in PR Adds built in CMaps and unifies the glyph mapping. #4259.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 76.47059% with 48 lines in your changes missing coverage. Please review.
✅ Project coverage is 62.59%. Comparing base (ff1af5a) to head (ed12eda).

Files with missing lines	Patch %	Lines
src/display/binary_data_factory.js	73.94%	37 Missing ⚠️
src/display/api.js	80.95%	8 Missing ⚠️
src/core/evaluator.js	84.61%	2 Missing ⚠️
src/core/jpx.js	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #20919      +/-   ##
==========================================
- Coverage   62.65%   62.59%   -0.06%     
==========================================
  Files         173      171       -2     
  Lines      121383   121284      -99     
==========================================
- Hits        76049    75922     -127     
- Misses      45334    45362      +28     

Flag	Coverage Δ
fonttest	7.66% <0.00%> (ø)
unittestcli	62.57% <76.47%> (-0.06%)	⬇️

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