Setup to make monitoring date picker component reusable in other stages (1)

What does this MR do?

In order to make date picker component reusable, its dependencies should be moved out of the other monitoring related files.

This change keeps most of the component logic the same, while at the same time reformatting the default time windows data structure to make then more portable.

It renames a few exported functions so the API is more clear for future readers.

Next step will be to move the component to vue_shared directory.

Screenshots

N/A

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

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

Requirement of #197879 (closed)