Adds promo check when opening payments tab

[NejcZdovc]

Resolves #12688

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).
• 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. (Ask a Brave employee to help if you cannot access this document.)

Test Plan:

1. start browser with LEDGER_VERBOSE=true
2. enable payments
3. close preferences
4. open preferences and go to payments
5. you should see an error that there is no promotion in the console.log

Reviewer Checklist:

• Request a security/privacy review as needed if one was not already requested.

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[codecov-io]

Codecov Report

Merging #13078 into master will decrease coverage by <.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master   #13078      +/-   ##
==========================================
- Coverage   56.26%   56.26%   -0.01%     
==========================================
  Files         278      278              
  Lines       27584    27585       +1     
  Branches     4497     4497              
==========================================
  Hits        15521    15521              
- Misses      12063    12064       +1

Flag	Coverage Δ
#unittest	56.26% <0%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
app/browser/api/ledger.js	57.09% <0%> (-0.03%)	⬇️

[bsclifton]

++

[bsclifton]

master c017bbb
0.22.x 5210561
0.21.x e8a67b3

[NejcZdovc]

0.21 twitch 8cc234f