Apply generic cosmetic filters from brave://adblock even in "Standard" Shields blocking mode

[antonok-edm]

This is actually the original issue reported in #19085, which morphed into a different problem because of an update to https://www.circleci.com and another report added as a comment...

...anyways, it should be possible to add a ###idname or ##.classname rule to the Custom Filters box in brave://adblock, and have that applied regardless of element first-party status even in Standard shields mode. This should also work for regional lists and lists added through custom subscriptions.

[stephendonner]

Verified PASSED using

Brave	1.37.37 Chromium: 98.0.4758.87 (Official Build) nightly (x86_64)
Revision	e4cd00f135fb4d8edc64c8aa6ecbe7cc79ebb3b2-refs/branch-heads/4758@{#1002}
OS	macOS Version 12.3 (Build 21E5196i)

Steps:

1. new profile
2. python3 -m http.server
3. saved the minimal HTML testcase locally
4. loaded it http://localhost:8000/Desktop/issue20177/issue20177-testcase.html (yeah, ignore the filename, had my wires crossed when naming it, but the test is valid).
5. confirmed I saw the text
6. from the text, added ###generic to brave://adblock
7. reloaded the test page
8. confirmed the text was hidden

example	example	example

---

Verified PASSED using

Brave	1.37.40 Chromium: 98.0.4758.87 (Official Build) nightly (64-bit)
Revision	e4cd00f135fb4d8edc64c8aa6ecbe7cc79ebb3b2-refs/branch-heads/4758@{#1002}
OS	Linux

Steps:

1. new profile
2. python3 -m http.server
3. saved the minimal HTML testcase locally
4. loaded it http://localhost:8000/Desktop/testcase2.html
5. confirmed I saw the text
6. from the text, added ###generic to brave://adblock
7. reloaded the test page
8. confirmed the text was hidden

example	example	example

---

Verified PASSED using

Brave	1.37.46 Chromium: 98.0.4758.87 (Official Build) nightly (64-bit)
Revision	e4cd00f135fb4d8edc64c8aa6ecbe7cc79ebb3b2-refs/branch-heads/4758@{#1002}
OS	Windows 10 Version 21H2 (Build 19044.1526)

Steps:

1. new profile
2. python3 -m http.server
3. saved the minimal HTML testcase locally
4. loaded it http://localhost:8000/Desktop/testcase2.html
5. confirmed I saw the text
6. from the text, added ###generic to brave://adblock
7. reloaded the test page
8. confirmed the text was hidden

example	example	example	example

[Uni-verse]

Verification Passed on Android using version:

1.37.105 Chromium: 100.0.4896.46 (Official Build) (32-bit)

Test Devices:
Samsung Galaxy S21 | Android 12
Samsung Galaxy Tab S7 | Android 11

Test Page: https://uni-verse.github.io/adblock_cosmetic_filters.html

• Able to view the html with ###generic text before apply adblock filter w/ default Shields
• Verified that text is hidden after applying custom filter ###generic in brave://adblock
• Verified that disabling shields will remove custom filter and show the html test page
• Verified that removing custom filter from brave://adblock will remove custom filter tag after relaunching app/new tab

Mobile

1	2

Tablet

1	2