Add Commented by to MR widget

Issue: #10294 (closed)

What does this MR do?

This MR displays a new column to of "commented by" into the MR widget

MR	Changes
!38580 (merged)	BE placeholder
!39237 (merged)	BE add data
current	FE
!39278 (merged)	Doc

Feature Flag

This feature is behind a feature flag and is turned on by default. You can enable and disable with the following:

rails c

Feature.enable(:approvals_commented_by) # Enable

Feature.disable(:approvals_commented_by) # Disable

Testing Case

1. Go to a Merge Request
2. Expand the MR widget

• There is a new "Commented by" column

• When there are no commented by users, it will be blank

Smaller Screen size

• The "Commented by" looks like this if there are users:

• There is no "Commented by" when there are no users:

Who are added?

commented_by are people within the approvers list who have made comments in the MR

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Closes #10294 (closed)