Tokens scoped to invokable scripts

__Proposal:__
Allow users to create tokens that have read, write permissions and allow you to create and delete invokable scripts. In the case where they're only using invokable scripts to query certain buckets (not using scripts in conjunction with the http package to call additional API endpoints and create other resources).
__Current behavior:__
User must use an all-access token.

__Desired behavior:__
Enable users to use scripts so multiple dev teams can query last data points with bucket/measurement as parameters. Without giving them the power of an all token.

From this post:
https://community.influxdata.com/t/custom-api-and-tokens/26065

No file, test, or entry point is named. Start with the proposal and its linked community post, then determine how scoped read/write permissions should cover invokable script creation and deletion. Done means users can query permitted buckets and measurements through scripts without an all-access token.

Written by the indexing model from the issue text.