feat(sentry-core): add support for w3c traceparent (#687) #1173

Job	Run time
Lints	27s
Test using Rust stable on ubuntu-latest	46s
Test using Rust stable on macos-latest	52s
Code Coverage	1m 50s
Check feature permutations using Rust stable on ubuntu-latest	21s
Build-test documentation	29s
Test using Rust stable on windows-latest	3m 28s
Check feature permutations using Rust stable on macos-latest	30s
Check feature permutations using Rust stable on windows-latest	3m 29s
Check / Test MSRV on ubuntu-latest	1m 34s
Check / Test MSRV on macos-latest	1m 11s
Check / Test MSRV on windows-latest	3m 10s
	18m 7s

Provide feedback