[Cashtab] Stop using port object to prevent port disconnect errors

Summary:
T3370

Looking into this more. Really we don't have any need to use the port object to maintain long lived connections. Cashtab extension requests are one-off msg passing. Chrome has method to support this, so use it instead.

Note: The port passing is preserved for address sharing as, in testing, it was nontrivial to remove this extension-side. Also, have not seen the port disconnect error for the address passing feature, so lower priority to patch.

Test Plan:
npm run extension
Navigate to components.cashtab.com
Click some of the CashtabBadge components and confirm extension pops up
Confirm Address Sharing works with accepting and requesting the address from the extension
Confirm you don't see 'port disconnect' error after lots of clicks

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Subscribers: emack, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D15042