feature: Add country flag for public IP

[azadevlab]

using MR style like - #494

Summary
This MR -

• adds country flag support (with disable/enable function)
• can specify IP update interval in minutes (minimum 1 minute due prevent spamming, but recommended to set it higher than 5 minutes)
• network icon hides once "Show copuntry flag" is enabled

PLEASE PAY ATTENTION THAT schemas was updated, YOU HAVE TO RE-COMPILE schemas/gschemas.compiled glib-compile-schemas schemas/

Old situation
no country flag for Public IP

New situation
country flag for IP can be set

Changes Made
added checkbox "Show country flag"
added box for setting Public IP update interval (min 1 , max 1440)

Testing
No startup errors
No errors during adding/removing items or when changing settings

Screenshots/Visual Changes

[azadevlab]

@corecoding hi Chris, please could you check this MR and merge it?

closes #488 (comment)

[corecoding]

@azadevlab I appreciate the work here (and the other PR as well). I am going to merge this PR but change a few things. I ended up spending some time (too much) on making the country flag the left most icon. I do like your addition to the Prefs - but may also limit the refresh rate. But please do take a look at the develop branch and let me know what you think.

[azadevlab]

@corecoding no, you're breathtaking! :) I'm really appreciate to you and all others who previously have worked on this extension, you're awesome, gents
this extension is fantastic and lovely

man, thank you one more time 🙏