Basic user quotas

[zsinnema]

Implement basic application user quotas based on Keycloak user / group attributes

base quotas are stored in the application in the values.yaml within the harness tree
the application can get the quotas and responds according to the quotas

example for Jupyterhub

harness:
  quotas:
    # sets the maximum number of workspaces for the user
    quota-ws-max: 5
    # sets the maximum number of workspaces open concurrently
    quota-ws-open: 3
    # sets the cpu guaranteed on a single workspace
    quota-ws-guaranteedcpu: 1
    # sets the cpu limit on a single workspace
    quota-ws-maxcpu: 1
    # sets the memory guaranteed on a single workspace
    quota-ws-guaranteedmem: 1
    # sets the memory limit on a single workspace
    quota-ws-maxmem: 1.5G
    # sets the storage dedicated to the user data
    quota-storage-max: 1G
...

[zsinnema]

the algorithm for determinating the correct quota values will use the biggest (max) quota on the lowest leaf of the quota
the quotas on user attributes will be of highest order (they will overrule the group quotas)

example with group and subgroups:
/Base {'quota-ws-max': 12345, 'quota-ws-maxcpu': 50, 'quota-ws-open': 1}
/Base/Base 1/Base 1 1 {'quota-ws-maxcpu': 2, 'quota-ws-open': 10}
/Base/Base 2 {'quota-ws-max': 8, 'quota-ws-maxcpu': 250}
/Low CPU {'quota-ws-max': 3, 'quota-ws-maxcpu': 1000, 'quota-ws-open': 1}

result: {'quota-ws-maxcpu': 1000, 'quota-ws-open': 10, 'quota-ws-max': 8}

quota-ws-maxcpu from path "/Low CPU" results in
--> overrules paths "/Base/Base 1/Base 1 1" and "/Base/Base 2" (higher value)
--> /Base quota-ws-max is not used because this one is not the lowest
leaf with this attribute (Base 1 1 and Base 2 are "lower")
quota-ws-open from path "/Base/Base 1/Base 1 1"
quota-ws-max from path "/Base/Base 2"