SHIP-0039: Command line option to set custom scheduler on `Build`/`BuildRun`

[adambkaplan]

Feature

Add option to set the pod scheduler for a BuildRun (and potentially Build). Depends on shipwright-io/build#1637.

Part of SHIP-0039

[Adarsh-jaiss]

/assign

[adambkaplan]

Moving to the next release milestone (v0.16.0) for now.

[rxinui]

Hey @Adarsh-jaiss, if you are busy dealing with another important issues, maybe i can take ownership to this issue as it is really similar from my last submission #309 (yet to be reviewed)

[rxinui]

/assign