DESIGN/EXECUTE - gitcoin.co/new loading indicator

### User Story

[comment]: # (As a , I want to so that .)
As a user of gitcoin.co/new, when I submit the form, the system doesnt immediately respond to let me know it's "thinking". Bc of this, I am left to wonder whether something broke or whats up? It makes me trust the system less.

### Why Is this Needed

[comment]: # (Describe the problem and why this task is needed. Provide description of the current state, what you would like to happen, and what actually happen)
*Summary*:
See user trust story above.

### Description

[comment]: # (Feature or Bug? i.e Type: Bug)
*Type*:
Improvement

### Current Behavior
[comment]: # (Describe what actually happened.)
No loading indicator

### Expected Behavior
[comment]: # (Describe what you expected to happen.)
Overlay with loading indicator is displayed while the system is thinking.
Overlay can be clicked out of, and it should go away when the system "stops thinking" (whether error, warning, or success)

### Definition of Done
[comment]: # (Any other information that would be useful, bullets are helpful.)
See above.

### Data Requirements
[comment]: # (How will we measure the success of this feature? What kind of tracking is needed for this feature (clicks, impressions, flag)?)
Will there be less double-bounty posts?

### Additional Information
[comment]: # (Any other information that would be useful, content, screenshots, etc.)
🖖