[WIP/PoC] Add FAAS semconv opt-in and AwsLambdaInstrumentor configuration

[tammy-baylis-swi]

Description

WIP/PoC

Adds FAAS semconv opt-in to the existing implementation for HTTP opt-in. The new attributes are based on aws-lambda.md semconv. Both FAAS and HTTP semconv opt-in are set dependingon on OTEL_SEMCONV_STABILITY_OPT_IN which is a comma-delimited string. Currently if set as "default" then both FAAS and HTTP use the old semconv, and any empty is default. Examples:

OTEL_SEMCONV_STABILITY_OPT_IN	http	faas
empty	old	old
"default"	old	old
"http"	new	old
"faas"	old	new
"faas/dup"	old	both
"http,faas"	new	new
"http/dup,faas/dup"	both	both
"http/dup,faas"	both	new

Adds AwsLambdaInstrumentor usage of the FAAS opt-in. Setting of span attributes in this instrumentor depends on span.is_recording() after the call to start_as_current_span. So I made the new _set_* methods for the FAAS opt-in do direct span.set_attribute calls though this is not as uniform.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

I've packaged a custom version of layer-python (e.g. release 0.4.0) with these changes and set OTEL_SEMCONV_STABILITY_OPT_IN before invoking an equipped AWS Lambda function.

Does This PR Require a Core Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[tammy-baylis-swi]

Closing this in favour of #2371.