Configure tls and add example for grpcio

[jaysonsantos]

This PR adds a new function to otlp's builder called with_tls in order to configure empty credentials on grpcio so it talks with https and not in a decrypted manner.
I think that for the future this with_tls could be used on tonic as well so it can configure the host for TLS in case the server you are talking to uses SNI.
Let me know if you have questions or something has o change there.

[codecov]

Codecov Report

Merging #450 (c0060c1) into main (8e0857d) will increase coverage by 0.52%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #450      +/-   ##
==========================================
+ Coverage   47.91%   48.43%   +0.52%     
==========================================
  Files          95       95              
  Lines        8739     8739              
==========================================
+ Hits         4187     4233      +46     
+ Misses       4552     4506      -46     

Impacted Files	Coverage Δ
opentelemetry-otlp/src/span.rs	17.77% <0.00%> (ø)
...ntelemetry/src/sdk/metrics/aggregators/ddsketch.rs	76.95% <0.00%> (ø)
opentelemetry/src/context.rs	62.09% <0.00%> (+30.06%)	⬆️

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[TommyCpp]

Might need to remove the example from the workspace and ask CI to check it separately.

[jaysonsantos]

@TommyCpp

Might need to remove the example from the workspace and ask CI to check it separately.

should I do it only on this example or for all of them?

[jtescher]

Looks reasonable, thanks