Add flow property updates ADR and specification extensions

[philipnbbc]

Details

This PR came about because an question was raised about whether the Flow source_id can be updated. The proposal is to allow it to be updated to fix incorrect values for example. This may be restricted by systems that sit in front of TAMS API that check permissions for example.

This PR offers some changes wrt updating Flow properties but proposes no change at this stage. Requirements may arise in future that changes this.

This PR adds endpoints for bit rate (see also #86) and flow collection properties. This is to make it consistent with other properties that are likely to be updated.

Pivotal Story (if relevant)

Story URL: https://www.pivotaltracker.com/story/show/188210268

Related PRs

Where appropriate. Indicate order to be merged.

Submitter PR Checks

(tick as appropriate)

• PR completes task/fixes bug
• API version has been incremented if necessary
• ADR status has been updated, and ADR implementation has been recorded
• Documentation updated (README, etc.)
• PR added to Pivotal story (if relevant)
• Follow-up stories added to git push --set-upstream origin philipn-flow-property-updatesPivotal

Reviewer PR Checks

(tick as appropriate)

• PR completes task/fixes bug
• Design makes sense, and fits with our current code base
• Code is easy to follow
• PR size is sensible
• Commit history is sensible and tidy

Info on PRs

The checks above are guidelines. They don't all have to be ticked, but they should all have been considered.