Action field defaults page

[gabestein]

Motivation

• So admins can specify default field values for actions

Requirements

• New "action defaults" page in community settings that groups all action config fields by action and allows community admins to fill out and save defaults for the community
• For any field in settings page, user can click a checkbox that indicates the field is secret and the value will not be shown to end users

Acceptance Criteria

• Write functions that encrypt/decrypt variables market as secret

[tefkah]

Whoops, did not see this issue before i typed out something!

See #1028 (comment)

In short: I think we should instead allow users to configure multiple sets of settings and have them choose 1 as the default, rather than only setting defaults. This is useful for eg HTTP action with many different authentication tokens, and the Email actions (can configure mail templates this way)