Propagate b3 parentspanid and debug flag

[srjames90]

Which problem is this PR solving?

• fixes x-b3-parentspanid and x-b3-flags don't get propagated #1338

Short description of the changes

• Adds parentSpanId and debug to the spanContext

[codecov]

Codecov Report

Merging #1346 into master will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1346      +/-   ##
==========================================
- Coverage   93.63%   93.62%   -0.01%     
==========================================
  Files         149      147       -2     
  Lines        4272     4190      -82     
  Branches      871      860      -11     
==========================================
- Hits         4000     3923      -77     
+ Misses        272      267       -5     

Impacted Files	Coverage Δ
...metry-core/src/context/propagation/B3Propagator.ts	100.00% <100.00%> (+2.32%)	⬆️
packages/opentelemetry-plugin-fetch/src/fetch.ts
...telemetry-plugin-fetch/src/enums/AttributeNames.ts

[srjames90]

Unrelated, but the test 'should gracefully handle an invalid b3 header' doesn't seem to be testing what we want.

[obecny]

Is there a situation when those 2 values will be set together ?

assert.strictEqual(context.getValue(DEBUG_FLAG_KEY), '1');
assert.equal(context.getValue(PARENT_SPAN_ID_KEY), 'Something else the undefined');

[srjames90]

Is there a situation when those 2 values will be set together ?

assert.strictEqual(context.getValue(DEBUG_FLAG_KEY), '1');
assert.equal(context.getValue(PARENT_SPAN_ID_KEY), 'Something else the undefined');

Yeah, added a test for both of them being set

[dyladan]

Forgot to add the reason I set my review status to "requested changes" is due to the undefined use of the traceflags second bit.

[obecny]

Thx for changes - the code is easier to read :).

If possible I would like to encourage you yet to rewrite description of unit test a bit. So they are more readable and are written in style of "when -> then". It also helps to document the code and to understand it faster whenever someone will try to fix the problem in future when tests are failing or need to refactor code. I have added 2 examples what I have on my mind, thank you

[obecny]

lgtm, thx for changes

[mayurkale22]

Added one small comment - going to provide LGTM and hope you can address prior to merging.

[srjames90]

Added one small comment - going to provide LGTM and hope you can address prior to merging.

done, thanks