Implement new contribution flow for unverified publishers

[NejcZdovc]

New logic: We never send contributions to unverified creators. However, we do allow users to take actions to tip or auto-contribute to these creators -- the difference is the user holds these tips/contributions in reserve within the browser, and the browser retries contributions once every 30 days (on the normal auto-contribute / monthly tip cycle), checking for newly verified creators. We never transmit any information about unverified creators or attention spent on their sites to any server. This information and all of the logic surrounding it is entirely client-side. Only verified creators get transmitted contributions.

Two releases: This change will be made in two releases, in order to accommodate an immediate hotfix (captured by this issue), and later, a complete fix that fully implements the retry logic. The key for the immediate hotfix is to make sure we preserve the tip/contribution data client side — and change some strings and other UX details — so that we can act upon older attention data in a future release.

[LaurenWags]

Verified passed with

Brave	0.58.20 Chromium: 71.0.3578.98 (Official Build) (64-bit)
Revision	15234034d19b85dcd9a03b164ae89d04145d8368-refs/branch-heads/3578@{#897}
OS	Mac OS X

• Using spec, verified that text was updated on panel and site banner
  
  

• Verified that Auto-Contribute line item in Wallet Summary Panel only shows sum of verified sites BAT

• Verified that Recurring Monthly Tips line item in Wallet Summary only shows the sum of verified sites BAT

• Verified that only the sum of verified auto-contributions and verified monthly recurring tips is subtracted from the wallet balance

• Verified that a new box displays on the wallet summary panel which shows the sum of BAT waiting for unverified publishers

• Verified this sum of unverified BAT was not removed from wallet balance
  

Verification PASSED on Mint 19.1 x64 VM using the following build:

Brave	0.58.21 Chromium: 71.0.3578.98 (Official Build) (64-bit)
Revision	15234034d19b85dcd9a03b164ae89d04145d8368-refs/branch-heads/3578@{#897}
OS	Linux

• Went through the same verification's @LaurenWags outlined above.

Verification passed on

Brave	0.58.21 Chromium: 71.0.3578.98 (Official Build) (64-bit)
Revision	15234034d19b85dcd9a03b164ae89d04145d8368-refs/branch-heads/3578@{#897}
OS	Windows 10

• Verified the text message in Rewards panel and site banner.
  
  

• Verified that Auto-Contribute line item in Wallet Summary Panel only shows sum of verified sites BAT
• Verified that Recurring Monthly Tips line item in Wallet Summary only shows the sum of verified sites BAT
• Verified that only the sum of verified auto-contributions and verified monthly recurring tips is subtracted from the wallet balance
• Verified that a new box displays on the wallet summary panel which shows the sum of BAT waiting for unverified publishers
• Verified this sum of unverified BAT was not removed from wallet balance