Quota management MVP

[tardieu]

To begin experimenting with quota management on a test cluster, we need to:

• define the quota tree,
• fix critical issues,
• update AppWrapper submission guidelines and tools.

Quota tree

To minimize complexity and disruption, we will start with a fixed quota tree consisting of three nodes and a single resource:

• a root node with a hard quota (total amount available in the cluster),
• a leaf node with the same quota as the root node (to be used as the default quota),
• a leaf node with a limited soft quota.

Remaining bugs

• Creation of the quota tree sets cpu and memory as default resources #549
• Releasing borrowed quota in a full or almost full cluster. #556

AppWrapper submission

• update helm tool, torchx-mcad, codeflare cli and sdk to support specifying a quota.

[z103cb]

I have opened #399 to cover the TODO from Remaining critical issues section.