Directives Used in Snippets are Reported via Telemetry

[mpstefan]

As a maintainer of NGF
I want to know what the most popular directives used in snippets in NGF
So that I can prioritize the most popular directives to be promoted to first-class configuration via Gateway API extensions.

Acceptance

• Every unique directive, a count of it's usage, and the context it was used in is reported in product telemetry.
• Only valid snippets are read and reported.
• The design for reporting directive data is reviewed to ensure we can derive the analysis we are looking for.