AWS SSM support

[enemycnt]

Description

Related Issue Or Context

Closes: #259

How Has This Been Tested? Testing details.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation

Checklist:

• I have commented my code, particularly in hard-to-understand areas.
• I have ensured that all acceptance criteria (or expected behavior) from issue are met
• I have updated the documentation locally and in chainbridge-docs.
• I have added tests to cover my changes.
• I have ensured that all the checks are passing and green, I've signed the CLA bot

[render]

Your Render PR Server URL is https://chainbridge-pr-263.onrender.com.

Follow its progress at https://dashboard.render.com/static/srv-cauqa776d9ksg8qj90j0.

[lgtm-com]

This pull request introduces 2 alerts when merging ad65872 into 470778e - view on LGTM.com

new alerts:

• 2 for Unused variable, import, function or class

[wainola]

Should we update the README to explain how to use this in development and in production?

[lgtm-com]

This pull request introduces 2 alerts when merging 8fe83a8 into 470778e - view on LGTM.com

new alerts:

• 2 for Unused variable, import, function or class

[lgtm-com]

This pull request introduces 2 alerts when merging 9643423 into 470778e - view on LGTM.com

new alerts:

• 2 for Unused variable, import, function or class