Instrument Content Editor toolbar

What does this MR do?

It instruments the Content Editor toolbar by tracking the action of executing a toolbar control. Every toolbar control should emit an execute event with the following data: the content type related to the control and an optional value attribute that provides more context on the result of executing the control.

The following table describes the structure of the snowplow event

Snowplow event structure

	action	category	label	property	value
Data description	execute_toolbar_control	[page where editor is used]	content_editor	[content_type]	[context data]
heading 3 example	execute_toolbar_control	projects::wiki::edit	content_editor	heading	3
bold example	execute_toolbar_control	projects::wiki::edit	content_editor	bold	null

How to test this MR?

• Enable the wiki_content_editor feature flag echo 'Feature.enable(:wiki_content_editor)' | rails c
• Edit a new or existing Wiki page in a project.
• Click the "Use new editor" button
• Test the instrumentation by clicking the toolbar buttons

Screenshots (strongly suggested)

This MR does not produce user-facing changes

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog.
• 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

Related to #329649 (closed)