Cleanup: remove column workspace_auto_off from table organizations

Add columns to table workspace

• autostart_enabled:bool default false
• autostop_enabled:bool default false
• autostart_at:timestamp with time zone default '0001-01-01- 00:00:00+00::timestamptz NOTE: this will include the user’s timezone
• autostop_at:timestamp with time zone default '0001-01-01- 00:00:00+00::timestamptz NOTE: this will include the user’s timezone

Add methods to querier.go:

• SetWorkspaceAutoStartEnabled(ctx context.Context, workspaceid string, when time.Time) error
• SetWorkspaceAutoStartDisabled(ctx context.Context, workspaceid string) error
• SetWorkspaceAutoStopEnabled(ctx context.Context, workspaceid string, when time.Time) error
• SetWorkspaceAutoStopDisabled(ctx context.Context, workspaceid string) error

Changes:

• Instead of a time.Time, will use a crontab-style representation for schedules. See create cron-style library or wrapper for workspace autostart / autostop #817.
• autostart_at and autostop_at will be renamed autostart_schedule and autostop_schedule respectively.
• autostart_schedule and autostop_schedule will allow NULL values, allowing autostart_enabled and autostop_enabled to be removed.
• We only need the UpdateWorkspaceAutostart and UpdateWorkspaceAutostop methods, passing nil as the schedule can be semantically equivalent to DisableWorkspaceAuto{Stop,Start}.