Add polish to url bar icons with rounded square corners

[rebron]

Description

The icons in the url bar are too round and should use our square icon design for consistency.

Design

Brave version (brave://version info)

Version/Channel Information:

• Can you reproduce this issue with the current release? yes
• Can you reproduce this issue with the beta channel? yes
• Can you reproduce this issue with the nightly channel? yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? n/a
• Does the issue resolve itself when disabling Brave Rewards? n/a
• Is the issue reproducible on the latest version of Chrome? n/a

Miscellaneous Information:

[simonhong]

Working now.

[stephendonner]

Verification PASSED using

Brave | 1.63.101 Chromium: 120.0.6099.199 (Official Build) nightly (x86_64)
-- | --
Revision | 8d3f0a563e185b6a763cc8e210ab24775dfb9047
OS | macOS Version 14.3 (Build 23D5043d)

Steps:

1. installed 1.63.101
2. launched Brave
3. launched new windows and set up the conditions (pinned sites, brave://settings, etc.)
4. repeat the above but in Dark mode

Light	Dark

[stephendonner]

I spun off the oblong, circular site-permissions "bubbles" over in #35191.

[kjozwiak]

Removing QA Pass-macOS as the above will need to be verified via 1.62.x now that it's been uplifted via brave/brave-core#21548. However, used #34957 (comment) as the needed verification for uplifting as per brave/brave-core#21548 (review).

The above requires 1.62.144 or higher for 1.62.x verification 👍

[LaurenWags]

Verified with

Brave | 1.62.144 Chromium: 120.0.6099.217 (Official Build) beta (x86_64)
-- | --
Revision | 75de8d953f6a5686e425d46d7f0dc9284dc1c064
OS | macOS Version 13.6.3 (Build 22G436)

Reproduced the issue using 1.62.143:

Dark Theme	Light Theme

Verified fix using 1.62.144:

Dark Theme	Light Theme

Encountered #35358 with light theme, but is not caused by the PR for this issue, it is a 1.62.x regression though.