[MS Teams] Add arbitrary text value support for Facts

[iamxeph]

Description

Make ms_teams_alert_facts have arbitrary text value for its 'value' by returning 'value' itself

Let's say you have configured the alerter like this:

alert_subject: "Test Alert for ElastAlert2"
alert_text: "body"
alert_text_type: alert_text_only
ms_teams_alert_facts:
  - name: Host
    value: agent.name
  - name: What to do
    value: Page your boss

Currently it outputs to MS Teams like this:

This PR change the output to this:

Checklist

• I have reviewed the contributing guidelines.
• I have included unit tests for my changes or additions.
• I have successfully run make test-docker with my changes.
• I have manually tested all relevant modes of the change in this PR.
• I have updated the documentation.
• I have updated the changelog.

Questions or Comments