This commit adds the following changes to workspace scheduling behaviour:
* CLI: updating a workspace TTL updates the deadline of the workspace.
* If the TTL is being un-set, the workspace deadline is set to zero.
* If the TTL is being set, the workspace deadline is updated to be the last updated time of the workspace build plus the requested TTL. Additionally, the user is prompted to confirm interactively (can be bypassed with -y).
* UI: updating the workspace schedule behaves similarly to the CLI, showing a message to the user if the updated TTL/time to shutdown would effect changes to the lifetime of the running workspace.
This PR adds fields to templates that constrain values for workspaces derived from that template.
- Autostop: Adds a field max_ttl on the template which limits the maximum value of ttl on all workspaces derived from that template. Defaulting to 168 hours, enforced on edits to workspace metadata. New workspaces will default to the templates's `max_ttl` if not specified.
- Autostart: Adds a field min_autostart_duration which limits the minimum duration between successive autostarts of a template, measured from a single reference time. Defaulting to 1 hour, enforced on edits to workspace metadata.
* Changes all public-facing codersdk types to use a plain int64 (milliseconds) instead of time.Duration.
* Makes autostart_schedule a *string as it may not be present.
* Adds a utils/ptr package with some useful methods.
