Only load http/https URLs when scanning a QR code from the URL bar

[kylehickinson]

Description:

Currently any valid URL scheme is loaded, we should restrict that to only http/https URLs.

Steps to Reproduce

1. go to https://brave.com/
2. click the url bar
3. delete all characters
4. click the scan QR code button
5. scan the attached QR code (javascript:alert(document.domain);)

Actual result:

For this QR code, it will do nothing because javascript schemes are only valid in a bookmarklet context.
For other URLs likely they will fail to load

Expected result:

Any non-http/https URL should be submitted as a search query to the users default search engine

Reproduces how often:

Always

[srirambv]

Verification passed on the following devices running 1.49 (23.3.15.17)

• Verified steps from issue description
• Verified scanning the QA code from issue description performs search on the SE and doesn't load it as a URL

iPhone 7+ (iOS 15.7.3)	iPhone XR (iOS 16.3.1)	iPad Pro (16.4 Beta 2)
6997-iPhone.7+.MP4	6997-iPhone.XR.MP4	6997-iPad.Pro.MP4