Deployment API now accepts updated_after and
updated_before filtering options which should
allow to limit selection to certain datetime range

This allows order_by updated_at on the Deployments API so users can
query for the most recent updates. It adds a database index to ensure
the feature is performant.

This API can be used for manually creating deployments, instead of being
limited to creating deployments using CI pipelines.

As part of these changes, I refactored some parts of the existing
deployments code. This ensures we reuse the same logic for creating
deployments in different places. We also move the deployments service
classes to a Deployments namespace, now that there are two service
classes.

We also make some changes to which deployments are displayed. Prior to
these changes, only deployments that were successful were displayed.
This can get very confusing when using deployments from external
systems, so we now show deployments regardless of their status. The
table to display deployments has also had some style/content changes to
display the deployments data in a more meaningful way.

Adds the updated_at attribute to responses from the API deployments
endpoints.

Replace all '9koXpg98eAheJpvBs5tK' occurrences with
'<your_access_token>' in API docs.

Replace all '9koXpg98eAheJpvBs5tK' occurrences with
'<your_access_token>' in API docs.

Adds sorting to deployments API through the `order_by` and sort
`fields`.

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Deployment and Play endpoints

See merge request !5825