Fix some minor UI issues

[AlikhanAliev]

• 1. We should remove all bottom dividers from last rows of all list views. @AlikhanAliev, please provide a list of the problematic views.
• 2. Bug: when I am trying to add a new user filter rule, the text field doesn't get focus
• 3. Bug: stop saving the last added custom filter URL, this is annoying. However, we should keep this functionality for the user filter and whitelist import dialogs.
• 4. Don't forget to restore the divider in the extensions list: https://uploads.adguard.com/up04_6exgv_Switches_and_dialogs_-_Android_app_-_New_extension_step_3.png

Mockups:

• DNS
• User scripts
• Filters

[chernikova-yana]

Bottom dividers
@admitrevskiy

• Home/Settings/DNS Filtering/SelectDNSserver/RecommendedDNSproviders/Quad9
• Home/Settings/StealthMode/description(Stealth Mode module protects your identity…)
• Home/Battery Usage/description(When AdGuard is on...)
• Home/Settings/Network/Proxy/description(A proxy server is...)
• Home/under the date and above Ads blocked

[admitrevskiy]

Done.