Add code style checker in unit test workflow

[mayurkale22]

These will help us to detect style related errors at an early stage instead of while executing unit or system tests.

[codecov-io]

Codecov Report

Merging #448 into master will decrease coverage by 0.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #448      +/-   ##
==========================================
- Coverage   94.96%   94.84%   -0.12%     
==========================================
  Files         148      148              
  Lines        9924     9703     -221     
  Branches      698      688      -10     
==========================================
- Hits         9424     9203     -221     
  Misses        500      500

Impacted Files	Coverage Δ
src/internal/util.ts	90% <0%> (-10%)	⬇️
src/tags/propagation/text-format.ts	94.11% <0%> (-0.89%)	⬇️
src/tags/propagation/variant-encoding.ts	95% <0%> (-0.84%)	⬇️
test/test-tag-map.ts	100% <0%> (ø)	⬆️
test/test-no-record-span.ts	100% <0%> (ø)	⬆️
test/test-metric-producer-manager.ts	100% <0%> (ø)	⬆️
test/test-exporter-buffer.ts	100% <0%> (ø)	⬆️
test/test-utils.ts	100% <0%> (ø)	⬆️
test/test-validation.ts	100% <0%> (ø)	⬆️
src/common/time-util.ts	100% <0%> (ø)	⬆️
... and 23 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4b7d14c...03dc474. Read the comment docs.