feat(plugin-http): add/modify attributes

[OlivierAlbertini]

Which problem is this PR solving?

• closes [plugin-http] attribute specs update #373
• closes [plugin-http] Create a span builder #394

Short description of the changes

• add new utility functions:
  • getAttributesFromHttpKind
  • getOutgoingRequestAttributes
  • getOutgoingRequestAttributesOnResponse
  • getIncomingRequestAttributes
  • getIncomingRequestAttributesOnResponse

Those method should be reused for the http2 plugin.
New specs comes with new network/http attributes
http.ts is more readable since we use those functions (in http plugin)
We also set some attributes sooner (before waiting the response)

• Sync tests with https plugins

After reading new specs, http plugin need to update parseResponseStatus function...
I created #642

[codecov-io]

Codecov Report

Merging #643 into master will decrease coverage by 0.67%.
The diff coverage is 92.61%.

@@            Coverage Diff             @@
##           master     #643      +/-   ##
==========================================
- Coverage   92.19%   91.51%   -0.68%     
==========================================
  Files         191      193       +2     
  Lines        9699    10021     +322     
  Branches      875      910      +35     
==========================================
+ Hits         8942     9171     +229     
- Misses        757      850      +93

Impacted Files	Coverage Δ
packages/opentelemetry-plugin-ioredis/src/enums.ts	100% <100%> (ø)
...ckages/opentelemetry-plugin-ioredis/src/ioredis.ts	100% <100%> (ø)
...ages/opentelemetry-plugin-mysql/test/mysql.test.ts	98.2% <33.33%> (ø)	⬆️
...n-postgres/opentelemetry-plugin-pg/test/pg.test.ts	94.27% <60%> (-0.03%)	⬇️
...ages/opentelemetry-plugin-redis/test/redis.test.ts	92.78% <60%> (-0.08%)	⬇️
packages/opentelemetry-plugin-ioredis/src/utils.ts	84.21% <84.21%> (ø)
.../opentelemetry-plugin-ioredis/test/ioredis.test.ts	94.63% <94.63%> (ø)
...kages/opentelemetry-metrics/test/mocks/Exporter.ts	66.66% <0%> (-33.34%)	⬇️
...ges/opentelemetry-plugin-https/test/utils/utils.ts	33.33% <0%> (-26.67%)	⬇️
...entelemetry-exporter-jaeger/test/transform.test.ts	100% <0%> (ø)	⬆️
... and 21 more

[OlivierAlbertini]

Example with new attributes:

[vmarchaud]

lgtm