Improves notifications for contribution

[NejcZdovc]

Resolves brave/brave-browser#2114

Native implementation: brave-intl/bat-native-ledger#179

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:

• enable rewards
• claim grant
• do a tip
• make sure that you see notification with correct amount

(start with reconcile interval flag)

• enable rewards
• claim grant
• set monthly amount to 50
• add site to ac table
• make sure that you see notification telling you that there was an error because you don't have enough funds

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

done

[NejcZdovc]

master (0.59) bc3ac42
0.58.x e26f4ad
0.57.x 57f93ea