Restore deleted sites

[NejcZdovc]

User can delete sites and recover them in the panel. In this issue we will implement button to restore all publishers, that will be shown in see all sites for auto contribute.

Button text: Restore <X> manually excluded sites

[NejcZdovc]

blocked on #967

[jenn-rhim]

Button text should be 'Restore All Excluded Sites': no need to mention 'manually' as we don't allow auto-excluded sites to be restored nor has the user been exposed to the notion of 'auto-exclusion'. Hence unnecessary cognitive noise.

If we could, adding this in front of the button would be nice:
Total Excluded Sites: xx

[srirambv]

Verification Passed on

Brave	0.55.11 Chromium: 70.0.3538.35 (Official Build) beta (64-bit)
Revision	28dcb499844fa40c28d5f62e337876cb936f79f5-refs/branch-heads/3538@{#678}
OS	Linux

• Verified excluded sites can be restored back by clicking on Restore all button

Verification passed on

Brave	0.55.12 Chromium: 70.0.3538.45 (Official Build) (64-bit)
Revision	cbdc32e4334458954e9def214d7e5fa1ca1960eb-refs/branch-heads/3538@{#830}
OS	Windows 7

Used test plan from brave/brave-core#434

Verified passed with

Brave	0.55.12 Chromium: 70.0.3538.45 (Official Build) beta(64-bit)
Revision	cbdc32e4334458954e9def214d7e5fa1ca1960eb-refs/branch-heads/3538@{#830}
OS	Mac OS X

Used test plan from brave/brave-core#434