AppSettings as tokens in operation parameters

[rllyy97]

Missing Feature

We should be able to add AppSettings as tokens to operation parameters.

Currently the only way to do this is through manually typing out the token string.

The token picker should have an AppSettings section similar to the WorkflowParameters section that contains all of the AppSettings in a logic app.

[axiomitdavid]

Also have intellisense for the appsetting expression in the expression editor