[feature request] Add command-line option for YurtHub to disable local cache and GC

[DrmagicE]

What would you like to be added:
Add command-line option for YurtHub to disable local cache and GC.

Why is this needed:
Base on this discussion #450, the YurtHub should also be deployed on the cloud side.
When deploying on the cloud side, caching apiserver response and the garbage collector is no longer needed, so we should provides an option to disable them.

There are some reasonable options here:

• --working-mode=cloud or
• --disable-disk-cache=false
• ..

Any advice?

others
/kind feature

[zzguang]

In case that yurthub may extend other features for edge nodes in future, I think "--working-mode" is more reasonable.

[rambohe-ch]

@DrmagicE It's make sense to me that add a new parameter for yurthub to specify where yurthub is working, edge or cloud.
--working-mode=cloud/edge (default value: edge) <-- agree +1

[rambohe-ch]

By the way, besides gc and cache feature, other features like discardcloudservice filter, some request handler of yurthub can also be disabled. so --work-mode mode maybe more reasonable.

[DrmagicE]

@rambohe-ch @zzguang Thanks for your advice. I think "--working-mode" is better. I will take over this issue.

[DrmagicE]

/assign @DrmagicE