Make role sync able to setup for each application permission and service account

[KeisukeYamashita]

What

I made a seperate API for configuring role sync for ApplicationPermissiond and ServiceAccount individually like below:

fiat:
   roleSync:
       enabled: true|false  // for backward compatibility
       applicationPermission:
           enabled: true|false
       serviceAccount:
          enabled: true|false

I've also refactored some tests.

Front50 access Fiat role/sync endpoint on application permission creation(which syncs all roles, very expensive endpoint) and service account creation(which only sync roles for specific roles, very light endpoint). I want to configure this seperatelly.

Why

Solves Make role sync settings to be configurable separately for service accounts and application permissions #6179.

If we disable fiat.roleSync, we will not be able to save the Spinnaker pipeline immediately after configuring the pipeline.
On the other hand, if we enable it, sometimes cause a performance issue and consume Fiat resources a lot. This behavior is reported in the community slack. https://spinnakerteam.slack.com/archives/CC101KSNP/p1585589301029500?thread_ts=1585577275.028800&cid=CC101KSNP