Dev - Get gist integration

[MILAN88888]

All Submissions:

• Have you followed the Everest Forms Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

This PR introduces the new get gist integration.

Dependency PR:

https://github.com/wpeverest/everest-forms-pro/pull/950

How to test the changes in this Pull Request:

1. Generate the api key from the https://getgist.com/
2. Initiate the connection same as other integration from settings.
3. Go to the form setting add connection, map fields
4. After submission check the contact list.

Types of changes:

• Bug fix (non-breaking change which fixes an issue)
• Enhancement (modification of the currently available functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully run tests with your changes locally?
• Have you updated the documentation accordingly?

Changelog entry

Dev - Get gist integration.

[NirajChaudhary143]

LGTM 👍

[riteelama]

LGTM 👍

[joshianup1]

LGTM 👍

[deepench]

LGTM 👍