[arclint] Fix arc lint for Cashtab

Summary:
There are some complications in linting Cashtab, which now includes ts files and js files. Some js files are pre-es6 js (build and config scripts related to create react app). These should all eventually be upgraded as well. For now, though, they are boilerplate.

Stop linting these files as ts linter does not handle pre-es6 js.

Adjust arc lint to include ts files for cashtab.

Test Plan: arc lint -- cashtab/**/*

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D17169