chore(plugin): postgres-pool plugin skeleton

[xiao-lix]

Which problem is this PR solving?

• Updates Request(plugin-postgres): pg-pool #418

Short description of the changes

• Add postgres-pool plugin skeleton, update structure of postgres-plugin folder

[codecov-io]

Codecov Report

Merging #473 into master will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #473      +/-   ##
==========================================
- Coverage   95.31%   95.26%   -0.05%     
==========================================
  Files         137      137              
  Lines        6973     6870     -103     
  Branches      596      596              
==========================================
- Hits         6646     6545     -101     
+ Misses        327      325       -2

Impacted Files	Coverage Δ
...opentelemetry-base/test/resources/resource.test.ts	100% <0%> (ø)	⬆️
...ges/opentelemetry-exporter-zipkin/src/transform.ts	100% <0%> (ø)	⬆️
.../opentelemetry-exporter-zipkin/test/zipkin.test.ts	100% <0%> (ø)	⬆️
...telemetry-scope-base/test/NoopScopeManager.test.ts	100% <0%> (ø)	⬆️
...entelemetry-exporter-zipkin/test/transform.test.ts	100% <0%> (ø)	⬆️
...-plugin-postgres/opentelemetry-plugin-pg/src/pg.ts	91.37% <0%> (ø)
...n-postgres/opentelemetry-plugin-pg/test/pg.test.ts	94.29% <0%> (ø)
...res/opentelemetry-plugin-pg/test/assertionUtils.ts	96.55% <0%> (ø)
...ugin-postgres/opentelemetry-plugin-pg/src/utils.ts	97.01% <0%> (ø)
...ugin-postgres/opentelemetry-plugin-pg/src/enums.ts	100% <0%> (ø)
... and 3 more

[dyladan]

I believe that the new sub packages you created are no longer referenced by the lerna.json file. You will need to add packages/opentelemetry-plugin-postgres/* to the packages list.

If someone with more lerna experience could confirm/deny this I would appreciate it

[mayurkale22]

I believe that the new sub packages you created are no longer referenced by the lerna.json file. You will need to add packages/opentelemetry-plugin-postgres/* to the packages list.

If someone with more lerna experience could confirm/deny this I would appreciate it

Maybe related to lerna/lerna#1191

[mayurkale22]

LGTM

[mayurkale22]

@open-telemetry/javascript-approvers Please review and approve.