Support only list the changed resources by maestro list API

[skeeey]

We may need a mechanism (e.g. a sequence ID for resources) to support only list the changed resources, by this way, the list API only returns the resources that have changed since the last synchronization.

e.g. there is a running source client, it has a resources list (r1, r2 and r3) with a sequence ID, the source client restart, during this time, the r2 is changed, after source client is started, the client sends a resync request with its resources sequence ID, the maestro server returns a list that only contains the r2

refer to open-cluster-management-io/ocm#483

[skeeey]

/cc @qiujian16 @clyang82 @morvencao @machi1990

[qiujian16]

how do you define latest changed?

[skeeey]

remove latest to eliminate the confusion and add some descriptions

[clyang82]

Currently, source client will get a full list by calling restful API when the source client is reconnecting