Add saving some plugin options to QSettings.

[alexeygribko]

This pull request adds saving of some plugin settings to QSettings instance which is already used for storing API Key and licence flag. This will fix the problem where you need to set all the flags again after restarting QGIS.

Updated flags:

• View Streetview links
• View Streetview address
• View Streetview image date
• View Streetview zoom control
• View Streetview pan control
• Streetview click to go

Tested in QGIS 3.28.10 on Windows and QGIS 3.34.6 on MacOS.