Improving the azure browse filter dropdown logic

[Benjin]

Refining and consolidating the logic to have more intuitive default logic. The overall logic is now:

• server always selects the first one in the list to make sure it's always populated, unless the user has explicitly cleared it
• all others default to no filter
• dropdowns are automatically scoped by any upstream filters that are set (subscriptions/resource groups/locations/servers)
• if a value is already selected and the upstream filters change, the selection stays if it's still in-filter or is cleared if not

Also adding several telemetry more points around Azure load times and errors

Note: because contents of subscriptions are loaded asynchronously, different servers may end up being selected each time depending on which subscriptions finish first. I thought it would be more confusing to swap the selection around to (e.g.) the first alphabetically as new entries loaded, so /shrug. The other dropdowns don't have that issue because they aren't set to always make a selection when available.

[github-actions]

PR Changes

Category	Main Branch	PR Branch	Difference
Code Coverage	50.51%	0.00%	$${\color{lightgreen} -50.51\% }$$
VSIX Size	11656 KB	11659 KB	$${\color{lightgreen} 3 KB \space (0\%) }$$
Webview Bundle Size	2988 KB	2984 KB	$${\color{lightgreen} -4 KB \space (0\%) }$$

[aasimkhan30]

Maybe we should create a helper function to track time. It would return another function that, when called, automatically measures the elapsed time and sends the action event with the mentioned properties.

[Benjin]

I like this thought. I'll make an issue to add some util stuff like that.

[kburtram]

Looks like a solid improvement to me!