Add telemetry for default browser choice

[data-sync-user]

For DMA countries ('BE','BG','CZ','DK','DE','EE','IE','EL','ES','FR','HR','IT','CY','LV','LT','LU','HU','MT','NL','AT','PL','PT','RO','SI','SK','FI','SE','GR'), for iOS or iPadOS versions of 18.2 and above, on first run of Firefox iOS, prior to displaying onboarding, check for the value of isDefaultApplication(for:) against the browser category

• If true - Set a metrics boolean to true that will be sent as part of the metrics ping to reflect the default state (Maybe we can have a similar implementation to https://dictionary.telemetry.mozilla.org/apps/fenix/metrics/metrics_default_browser

• ). Also set another boolean to true that will also be sent as part of the metrics ping to reflect the choice screen attribution state(metrics.choice_screen_acquisition?). null values on both of these booleans will reflect the fact that it was not set one way or another. Typically metrics.choice_screen_acquisition is set and is unlikely to change in the life of the browser whereas metrics.default_browser could change if we decide to implement a yearly check for set to default (could be a subsequent bug)

• If false - set a metrics boolean to false that will be sent as part of the metrics ping (Maybe we can have a similar implementation to https://dictionary.telemetry.mozilla.org/apps/fenix/metrics/metrics_default_browser

). Also set another boolean to false that will also be sent as part of the metrics ping to reflect the choice screen attribution state(metrics.choice_screen_acquisition?). null values on both of these booleans will reflect the fact that it was not set one way or another.

┆Issue is synchronized with this Jira Task