Add Markdown custom field type

[MeganerdDev]

Closes: #4006

What's Changed

• Added new custom field type for Markdown
  • Reused CommentField
  • Reused SmallTextarea widget -> not required for PR
• Apply markdown render to template

NOTE

• I think still we need to perform render_markdown() to test for script injection similar to custom_fields.py#L588 since that doesnt sanitize/check the field.label data?

TODO

• Explanation of Change(s)
• Added change log fragment(s) (for more information see the documentation)
• Attached Screenshots, Payload Example
• Unit, Integration Tests
• Documentation Updates (when adding/changing features)
• Example Plugin Updates (when adding/changing features)
• Outline Remaining Work, Constraints from Design

SCREENSHOTS

[MeganerdDev]

Definitely open for feedback!

• I tested this on Nautobot v1.5.22b1 to be working
• I am using the SmallTextarea widget, which could instead just be the default widget

[bryanculver]

At @lampwins' feedback, this can be included as a part of 1.6.

[bryanculver]

PR might look ugly until #4020 goes in.

[glennmatthews]

Looks both straightforward and useful - my favorite type of PR! :-)

[glennmatthews]

Oh oops, looks like our CI isn't checking for it in develop-1.6 yet - could you please add a changes/4006.added changelog fragment as part of this PR?

[MeganerdDev]

Oh oops, looks like our CI isn't checking for it in develop-1.6 yet - could you please add a changes/4006.added changelog fragment as part of this PR?

Thanks Glenn, you previously reminded me on another pull request on the changelog fragment. I'll try and get that jammed in my brain! Fragment ./changes/4006.added added