Add support to block scripts individually

[cezaraugusto]

fix brave/brave-browser#4336 (Too much bottom padding on scripts details view)
fix brave/brave-browser#4228 (Different number of scripts blocked in main view and detailed view)
fix brave/brave-browser#3431 (Change Shields numbers to count FQDNs rather than total requests)
fix brave/brave-browser#3367 (Show domain / subdomain not the full path for HTTPS detail view)
fix brave/brave-browser#3239 (Widen Shields panel to avoid text wrapping)
fix brave/brave-browser#2371 (Remove Block all text when there are no entries)
fix brave/brave-browser#3174 (Script blocked count included allowed scripts as well)
address brave/brave-browser#2996 (Surface script blocking shortcuts to "Allow once", fix scripts functionality, focus indicators, and scroll)

Test Plan:

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated.

[cezaraugusto]

closing in favor of #2485