When linking to LH docs, include utm parameters for analytics

Right now when we link to the LH docs we don’t include any tracking information. For example:

https://developers.google.com/web/tools/lighthouse/audits/has-viewport-meta-tag

We could include utm parameters to better understand how visitors arrived at the docs and why. For example:

https://developers.google.com/web/tools/lighthouse/audits/has-viewport-meta-tag?utm_source=lighthouse&utm_medium=extension&utm_content=failure

Ideally we’d use utm_medium to differentiate the Chrome extension from the Audits panel in Dev Tools. Not sure if the code is self-aware enough to make this distinction.

Other params: utm_source always lighthouse to indicate that we sent users there from this tool, and utm_content to identify why users were sent to the docs (the audit failed, passed, maybe specific details about the failure reason).

cc @paulirish @patrickhulce @kaycebasques

[kdzwinel]

As discussed on the eng meeting - we are going to include environment info in the build time (instead of detecting it in the runtime as I originally proposed).

[rviscomi]

^ small correction: utm_source should always be lighthouse, but we should customize the utm_medium param to match the environment