Refactored and migrated Rewards category from category to type

[tmancey]

Fixes brave/brave-browser#6350

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:

• Confirm Auto Contributions work as expected after an upgrade
• Confirm Pending Contributions (sites in the pending list) work as expected after an upgrade
• Confirm Auto Contributions work as expected for a fresh install
• Confirm Pending Contributions (sites in the pending list) work as expected for a fresh install

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]

nit: I would place every param in separate line as it's easier to read for me. Like this

return base::StringPrintf("INSERT INTO %s (%s) SELECT %s FROM %s;",
    to.c_str(),
    comma_separated_to_columns.c_str(),
    comma_separated_from_columns.c_str(),
    from.c_str());

[NejcZdovc]

1. components/brave_rewards/resources/extension/brave_rewards/background/events/rewardsEvents.ts line 101 (category -> type)

2. components/brave_rewards/resources/page/brave_rewards_page.tsx line 205 (category -> type)

3. components/definitions/chromel.d.ts line 128 (category -> type)

4. components/definitions/rewards.d.ts line 193 (category -> type) and Category to RewardsType. Category can be deleted

5. please add migration tests like we had them for previous version. This way we know that db files and structure is correct