recognize when //# sourceMappingURL is percent-encoded

[cspotcode]

TypeScript 4.1.1 started percent-encoding the filenames in //# sourceMappingURL

Before TS 4.1.1:

//# sourceMappingURL=foo bar.js.map

After TS 4.1.1

//# sourceMappingURL=foo%20bar.js.map

Changes made to support --transpiler (#1160) effectively avoided this issue. We computed where we thought the comment should begin, but if it wasn't at that position, we simply appended our sourceMappingURL comment, overriding whatever was already there. This means if a path was percent-encoded, we didn't care: we appended, overrode, and users were happy.

Nevertheless, this PR implements logic to percent-encode the path and check for a sourceMappingURL comment at that offset.

The new logic is:

• check based on non-percent-encoded path. If found, replace the comment
• check based on percent-encoded path. If found, replace the comment
• If neither found, append our sourceMappingURL comment after any comment that might already be there

See also: #1322

[codecov]

Codecov Report

Merging #1330 (e813ef7) into main (6b8323e) will increase coverage by 0.20%.
The diff coverage is 100.00%.

Impacted Files	Coverage Δ
src/index.ts	78.64% <100.00%> (+0.55%)	⬆️