Fix parse profile-update-interval http header

[AlexFozor]

Currently, when importing a profile via the clash(meta)://install-config intent, the application hardcodes the update interval to 0. It also ignores the standard Profile-Update-Interval HTTP header, leaving auto-updates disabled by default.

Fixes:

• Parse Profile-Update-Interval HTTP header (in hours) on fetch;
• Parse update-interval URI param (in minutes) from intents;
• Enforce a 15 min minimum bound to prevent server DDoS;
• Safely handle malformed inputs and allow <= 0 to explicitly disable updates.

[VVaraiotoko]

@AlexFozor @wwqgtxx I am a user with little programming knowledge, but is it possible that this commit broke the auto update interval setting? Since the commit was merged, there have been several posts about malfunctions of auto update interval. Could you please take a look?
#742 #746 #751 #756

[AlexFozor]

#757