Update Intentions form

### Overview of issue ###

- All inputs/dropdowns should be of equal height
- Remove separator from above the form actions (save, delete, etc.)
- Remove separator from above the description textarea
- Move the description input to be underneath the radio cards
- Update sizing and spacing of "Source" and "Destination headings"
- Update sizing of "Source service" and "Desination service" subheadings
- Increase space between headings and subheadings
- Move helper text to be below input label but above the actual text input
- Color of separators in permissions modal should be updated to our light border grey color

### Mockup of desired styling ###
**L4**

**Application aware**

**Permissions modal**

This task is applicable to both the create and edit forms.

[Figma file](https://www.figma.com/file/eCFbEIVSIuM1QuCHhndw8X/Hacktoberfest?node-id=1%3A78)