[mongodb] implement semantic db conventions

[naseemkullah]

Which problem is this PR solving?

• partially [pg + pg-pool] Update DB semantic conventions #116

Short description of the changes

• adhering to spec, worth noting: split ns to populate db.name and db.mongodb.collection attributes

[markwolff]

Looks great!

[codecov]

Codecov Report

Merging #187 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #187      +/-   ##
==========================================
- Coverage   95.23%   95.22%   -0.02%     
==========================================
  Files          93       93              
  Lines        4767     4756      -11     
  Branches      493      492       -1     
==========================================
- Hits         4540     4529      -11     
  Misses        227      227              

Impacted Files	Coverage Δ
node/opentelemetry-plugin-mongodb/src/types.ts	100.00% <0.00%> (ø)
node/opentelemetry-plugin-mongodb/test/utils.ts	91.17% <0.00%> (ø)
node/opentelemetry-plugin-mongodb/src/mongodb.ts	95.83% <0.00%> (ø)

[obecny]

@naseemkullah pls have a loot why is it failing - looks like might be a valid failures now ?

[naseemkullah]

Thanks @obecny

Seems like the namespace can be a MongoDBNamespace which is not available in definitely typed. In any case, always coercing to a string seems to have fixed the issue.