WIP: Confirmations UI integration

[ryanml]

Target PR: #1469

A few things need to be accomplished for this integration:

• The client side state/react code should be updated to accommodate multiple grants (Settings/Panel)
• The new ledger server response of a list of grants with a discerning type attribute (one for ads, one for regular grant claim) should be parsed and filled in to an updated state att grants_ appropriately.
• Code in native-ledger, web-ui, and rewards service implementation should have its methods updated to handle a list of grants as opposed to a single one.

Visual preview:

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
  • Windows
  • macOS
  • Linux
• Verified that these changes pass automated tests (npm test brave_unit_tests && npm test brave_browser_tests) on
  • Windows
  • macOS
  • Linux
• 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

Test Plan:

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

cc: @jsecretan @tmancey @emerick

[ryanml]

@tmancey @jsecretan was having some upstream issues working off of this PR while tracking the confirmations branch, I'm finishing this on another branch.