Make wayback url request to use per-profile SharedLoaderFactory

[simonhong]

With this factory, traffic to the Internet Archive will use tor
proxy in private(tor). and set cookie disallowed.

Resolves brave/brave-browser#8419

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Android
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that these changes pass automated tests (unit, browser, security tests) on
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that all lint errors/warnings are resolved (npm run lint)
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone
• Public documentation has been updated as necessary. For instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protection-Mode
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-compatibility-issues-with-tracking-protection
  • https://github.com/brave/brave-browser/wiki/QA-Guide

Test Plan:

1. Launch tor window
2. Load www.brave.com/bo
3. Capture network request by using wireshark or any other network intercepter
4. Verify that traffic to the Internet Archive(brave-api.archive.org) uses tor proxy
5. With Charles intercepter, it can't capture brave-api.archive.org url request.

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated.

[kjozwiak]

Reproduced the original issue on macOS 10.15.3 x64 using the following build:

Brave	1.7.22 Chromium: 80.0.3987.122 (Official Build) nightly (64-bit)
Revision	cf72c4c4f7db75bc3da689cd76513962d31c7b52-refs/branch-heads/3987@{#943}
OS	macOS Version 10.15.3 (Build 19D76)

When visiting https://brave.com/bo in a Tor window and selecting Check for saved version, you'll notice that https://brave-api.archive.org is being listed in Charles.

Verification PASSED on macOS 10.15.3 x64 using the following build:

Brave	1.7.32 Chromium: 80.0.3987.122 (Official Build) nightly (64-bit)
Revision	cf72c4c4f7db75bc3da689cd76513962d31c7b52-refs/branch-heads/3987@{#943}
OS	macOS Version 10.15.3 (Build 19D76)

Basically ensured that https://brave-api.archive.org/ isn't being listed in Charles Proxy when using the Tor window. Double checked with @simonhong and ensured that's the expected behaviour.