Buildbot hardware/cloud needs

[shoaibkamil]

This is intended to start a discussion to figure out what kinds of HW or cloud builders we need to 1) increase OS/backend/etc coverage and 2) reduce turnaround time by increasing the number of buildbots.

Some obvious needs:

• more Linux & windows buildbots (possibly utilizing cloud instances?)
• newer GPU hardware in buildbots (again, could be possible with some cloud providers)
• newer versions of macOS and mac HW, including Apple silicon

Tagging @steven-johnson and @abadams to add more.