[MM-57918] Add Metrics for Primary Platform

[JulienTant]

Summary

Exposes 2 new metrics:

• mattermost_primary The total number of active users who selected Mattermost as their primary platform.
• msteams_primary The total number of active users who selected Microsoft Teams as their primary platform.

In those definitions, active = has a token set.

There's a lot of "noise" because I had to move a few constants in storemodels to be able to reuse them in the store package.

Ticket Link

https://mattermost.atlassian.net/browse/MM-57918

[JulienTant]

@sbishel before you ask... :P I ran a test with 25K users, the whole GetStats() was between 30ms to 40ms (I changed the updateMetrics constant to 1minute for my tests and waited 10min to get enough sample data)

Results looks like this:

msteams_connect_app_connected_users 25428
msteams_connect_app_mattermost_primary 15946
msteams_connect_app_msteams_primary 9482

[lindy65]

Thanks for adding the QA-deferred label @JulienTant - this will be tested post-merge.

[JulienTant]

gentle ping @mgdelacroix ; I have a second PR coming that changes the same code 😅

[JulienTant]

Thanks @mgdelacroix I applied aliases, much easier to read indeed!