Move data from ledger_state into preferences

[NejcZdovc]

Resolves brave/brave-browser#9869
Resolves brave/brave-browser#9750
Resolves brave/brave-browser#7165

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-Protections
  • 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:

plan 1:

• start browser from mater
• enable rewards
• set values in AC settings
• close the browser
• switch to this PR
• start the browser
• go to AC settings and make sure that all are the same
• go rewards internals and make sure that wallet info matches as well
• (try different upgrade paths as well)

plan 2:

• enable rewards
• claim grant
• make sure that you see total balance with rates correctly

plan 3:

• enable rewards
• go to unverified publisher and open tip and monthly banner. Make sure that you see default values (currently 1, 10, 100) in there

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.

[NejcZdovc]

this fixes brave/brave-browser#9750

[kylehickinson]

iOS looks good to me. will require a few changes on client side

[bridiver]

the chromium_src changes are fine, but I think we're missing most of the benefit of using prefs here by keeping async methods going back and forth to access every value

[NejcZdovc]

CI passed on window, linux and ios. Restarting macos and android