Feature Flag evaluation event

[dyladan]

First draft of feature_flag.evaluation event from the feature flag semantic conventions working group. Based on proposal here: https://docs.google.com/document/d/1sBDD-uifx-Qy0NxtwRcrRAQ48sHQS9dTp6tpArQsoZg/edit

Summary of changes:

• Replace feature_flag.provider_name with feature_flag.provider.id
• Rename feature_flag to feature_flag.evaluation
• Add attributes to feature_flag.evaluation
  • feature_flag.context.id
  • feature_flag.environment.id
  • feature_flag.value
  • feature_flag.version
• Remove feature flag span event

[askpt]

I added a couple of comments; otherwise, it looks good.

[askpt]

As discussed, I suggested to rename to "The lookup key of the feature flag."

[askpt]

I suggest leaving this open. Using an "id" means it is "blocked" only to use IDs, and we can potentially use it for names or other semantically valid values.
I would allow you to use the following examples:
["provider-1", "guid_here", "provider-v1"]

[beeme1mr]

Suggested change

	- id: feature_flag.environment.id
	type: string
	stability: experimental
	examples: ["proj-1", "ab98sgs"]
	brief: >
	The identifier of the environment which the feature flag belongs to in a flag management system.
	- id: feature_flag.flag_set.id
	type: string
	stability: experimental
	examples: ["proj-1", "ab98sgs", "service1/dev"]
	brief: >
	The identifier of the flag set, which the feature flag belongs to in a flag management system.

A flag set is defined here as `A collection of related flags. This grouping helps organize feature flags based on their intended use, facilitating easier management and deployment.