Brave should be brave:// handler

[bbondy]

Description

Clicking on brave:// links should open in Brave.

Steps to Reproduce

1. Post a brave:// link Slack like brave://flags
2. Click on it

Actual result:

Nothing happens after you click to allow to open the link in Slack.

Expected result:

The link should open in Brave.

Reproduces how often:

Always

Brave version (brave://version info)

0.55.18

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? no
• Is the issue reproducible on the latest version of Chrome? n/a

Additional Information

We need to register fro the brave:// protocol

[cndouglas]

Duplicate of #326