Adapt code for TypeScript 3.7

Created by: felixfbecker

Migrate code to work with TS 3.7. This means if the build fails for our nightly upgrade Renovate PR, it is a compiler bug.

Created by: codecov[bot]

Codecov Report

Merging #5829 into master will increase coverage by 0.43%. The diff coverage is 44.44%.

@@            Coverage Diff             @@
##           master    #5829      +/-   ##
==========================================
+ Coverage   39.09%   39.53%   +0.43%     
==========================================
  Files        1169     1168       -1     
  Lines       58774    58110     -664     
  Branches     5746     5746              
==========================================
- Hits        22979    22974       -5     
+ Misses      33668    33009     -659     
  Partials     2127     2127

Impacted Files	Coverage Δ
web/src/repo/blob/Blob.tsx	0% <0%> (ø)
browser/src/libs/code_intelligence/extensions.tsx	82.43% <80%> (ø)
migrations/bindata.go