rewards and other custom chrome:// pages need favicon

[LaurenWags]

Description

Custom chrome:// pages need favicons. For pages like Rewards, which is included in the on-boarding flow, this should be done sooner rather than later, it looks bad without a favicon.

Steps to Reproduce

1. Navigate to chrome://rewards or chrome://adblock

Actual result:

No favicon:

Expected result:

Custom pages should have favicon like welcome page.

Reproduces how often:

easy

Brave version (chrome://version info)

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

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds? yes
• Does it reproduce on browser-laptop? n/a

Website problems only:

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

Additional Information

Similar to #1278 but that issue is specific to Task Manager.

[srirambv]

Action items from @davidtemkin

We should create new favicons (most obviously visible in tabs, but also potentially in bookmarks, etc) for pages like:

-- Rewards (currently a generic document icon)
-- Settings (currently the Chrome-default icon)

I assume there are others.

It looks like we already have such an icon for brave://welcome, which is great.

[NejcZdovc]

fixes in brave/brave-core#756

[LaurenWags]

@rossmoody @NejcZdovc could one of you add a test plan for this issue please?

[NejcZdovc]

@LaurenWags test plan is quite simple. Go to rewards setting page and make sure that settings tab has rewards logo as favicon

[LaurenWags]

thanks @NejcZdovc ! Wasn't sure if other pages were included with this issue as well.

[rossmoody]

Yeah maybe the scope of this one could be just for the rewards favico. We have a similar issue with a larger collection that might need revisited soon: #1278

[GeetaSarvadnya]

Verification pased on

Brave	0.59.12 Chromium: 72.0.3626.17 (Official Build) beta (64-bit)
Revision	08d2140079f8db14c9eb885a803d231b1a30e817-refs/branch-heads/3626@{#315}
OS	Windows

• Verified the STR mentioned in the description
  
• Favicon for welcome page is missing (Logged new issue Favicon for welcome page is missing in 0.59.12 #2747)

Verrification passed on

Brave 0.59.12 Chromium: 72.0.3626.17 (Official Build) beta (64-bit)
Revision 08d2140079f8db14c9eb885a803d231b1a30e817-refs/branch-heads/3626@{#315}
OS Linux

• Verified the STR mentioned in the description
  

Verification passed with

Brave	0.59.14 Chromium: 72.0.3626.28 (Official Build) beta(64-bit)
Revision	997b1040b63bac324e815797ba52be0cd8f616ed-refs/branch-heads/3626@{#461}
OS	Mac OS X

• Per rewards and other custom chrome:// pages need favicon #1466 (comment) and rewards and other custom chrome:// pages need favicon #1466 (comment) only verified brave://rewards page favicon with this issue using STR from description