Add DevOps metric Lead time for changes

[Sebastiaan127001]

Lead time for changes = average lead time of changes completed in a certain time period.

Rationale (why measure the lead time for changes):

• The shorter the lead time of changes, the sooner the new features can be used. Also, the shorter the lead time of changes, the fewer changes are in progress at the same time. Less context switching is needed and the risk of interfering changes is reduced.

Parameters:

• Number of days ago (time period)

Sources:

• Jira
• Azure DevOps

Timestamps to use:

• Start of the change:
  • In progress date
• End of the change:
  • Resolution date

Filters:

• Types of issues, etc via a JQL (same as for the issues metric).

Out of scope:

• GitLab does not support the issues metric at the moment, so we're also not going to implement GitLab support for the lead time metric for now.