chore: make doc and data optional for cross build

[eagleoflqj]

libchewing uses chewing-cli to generate binary dictionaries from text files. When cross build (e.g. for wasm), the cli is not a natively-executable program, so the generation step needs to be skipped. Dictionaries can still be built natively and copied to wasm package.
The PR introduces BUILD_DATA that defaults to ON so that current behavior is preserved and it's easier to skip the data generation step.
BUILD_DOC is not as important as BUILD_DATA but also provides some convenience, as I'm not distributing man pages to the website that runs chewing wasm.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.06%. Comparing base (51fb091) to head (08655eb).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #789   +/-   ##
=======================================
  Coverage   92.06%   92.06%           
=======================================
  Files          37       37           
  Lines        9252     9252           
=======================================
  Hits         8518     8518           
  Misses        734      734           

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[kanru]

Thanks!

I'm very interested in your wasm build and how you plan to use it! Does the wasm build work out of the box?

[eagleoflqj]

I'm very interested in your wasm build and how you plan to use it!

I've deployed wasm build of fcitx5-chewing to https://fcitx-contrib.github.io/online/
Usage: Click Plugin Manager button and download chewing, then upload it to the rectangle area. Select chewing input method and get the same experience with desktop fcitx5-chewing.

Does the wasm build work out of the box?

Wasm build could have multi-thread disabled or enabled. I choose to disable it so that it can be ran without specific HTTP response headers (COEP and COOP) set by server, in the hope that it can be embedded in more websites. That means for every usage of multi-thread, I have to patch it to be single-thread. See my current patch for libchewing as an example, in which I change the thread spawn to a direct function call.

[kanru]

Thanks. This is so cool!

If you'd like to contribute a wasm patch I will merge it. I was planning to add a wasm demo on the website anyway 😄

P.S. I played a bit and it seems the current version is using built-in fallback dictionary instead of the files from the plugin.