Ensuring publishers file is read from as little possible

[ryanml]

We have publisherInfoData as an in-memory storage of the publisher verification data. When the publishers file is written to, this variable receives a copy of the information. We should look to this variable first for the data rather than reading from the file. In the case that we restart the browser, we should read the file but once then copy that info in to memory.

This gives a max file read per session of 1.

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:

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

[bsclifton]

++ so that we can get a new build

[bsclifton]

master d603250
0.24.x d7b2aec
0.23.x 7c7d573

[jasonrsadler]

I know I'm late to the party, but for future ref:
Is state getting updated at all in updatePublishers?

[ryanml]

Good spot. It doesn't hurt anything at the moment but we can change this in a future PR.