Use PathCapabilities for default configuring append mode for RollingFileSystemSink

RollingFileSystemSink uses a filesystem to store metrics. The key allow-append is disabled by default, but if enabled, new metrics can be appended to an existing file.

Given that we can have the PathCapabilities interface, we can change the default of allow-append mode depending on the support of the append operation decided by the FileSystem.hasPathCapability() call