Trigger filter update when it gets enabled (AdGuard for Mac)

[neshumov]

Issue Details

When user enables a filter, the version that gets applied may not be the most recent one.
The latest version is downloaded only if user manually triggers update of all enabled filters, or when the automatic update check runs according to update interval configured in the user’s settings.
As a result, user may work with outdated filter rules for extended period of time after enabling a filter.

Proposed solution

Add automatic update check for filter immediately after the user enables it
This update check should:

1. be scheduled approximately 5 seconds after filter is enabled (not executed instantly)
2. target only the specific filter that was enabled

Alternative solution

No response