Headers for responses should be case-insensitive

[Brandon-T]

Description:

• Currently when Brave-iOS parses headers, it parses them case-insensitive

Steps to Reproduce

1. None

Actual result:

• Headers are Case-Sensitive parsed which can cause hidden bugs

Expected result:

• Should parse headers case-insensitive

Test Plan:

• In the PR :)

[Uni-verse]

Verified on iPhone X running iOS 16.3.1 using version 1.51 (23.5.11.17)

Using Test Plan in #7395 (comment)

NTP Backgrounds

• Ensured that background images on NTP are showing
• Ensured that sponsored images are showing on NTP
• Ensured that disabling background images in settings will not display them on NTP
• Ensured background/sponsored image are shown while using VPN

Example	Example	Example	Example	Example	Example

Adblock lists

• Ensured that page has true for all values with shields up and null with shields down when loading https://test-pages.privacytests.org/tracking_content.html.
• Ensured that app launches relatively quickly with many filters enabled in the content filtering.
• Ensured that cosmetic filtering is working when loading twitter.com or reddit.com
• Ensured that script loading test page is passing, showing true when shields are up and null when shields down - https://dev-pages.brave.software/filtering/scriptlets.html

Example	Example	Example	Example	Example	Example

Playlist Sharing

• Confirmed downloading and saving a shared playlist is working using bsa-sample playlist.
• Confirmed shared playlist folder loads in Brave Playlist and user is able to use playback.
• Confirmed deleting shared playlist folder.

Example	Example	Example	Example