This commit fixes source maps for files that contain emojis.
This is done by updating "deno_ast" to "0.14.1" for the case
of "--no-check" flag (ie using SWC emit) and by overriding
TSC's default base64 encoder (which turned out to be buggy)
for the type checking case.
Covered ranges were not merged and thus it appeared that some lines
might be uncovered. To fix this I used "v8-coverage" that takes care
of merging the ranges properly. With this change, coverage collected
from a file by multiple entrypoints is now correctly calculated.
I ended up forking https://github.com/demurgos/v8-coverage and adding
"cli/tools/coverage/merge.rs" and "cli/tools/coverage/range_tree.rs".
