* 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.
* Adds a `bump` command to extend workspace build deadline
* Reduces WARN-level logging spam from autobuild executor
* Modifies `cli/ssh` notifications to read from workspace build deadline and to notify relative time instead (sidestepping the problem of figuring out a user's timezone across multiple OSes)
* Shows workspace extension time in `coder list` output e.g.
```
WORKSPACE TEMPLATE STATUS LAST BUILT OUTDATED AUTOSTART TTL
developer/test1 docker Running 4m false 0 9 * * MON-FRI 15m (+5m)
```
