[Searchable Snapshot] Implement disk reservation logic to be used for local file system cache

[aabukhalil]

Referring to #4964,

Cache Disk reservation logic will impact all of:

• NodesStats as fs stats need to take into consideration the cache reserved size
• DiskThresholdDecider once monitor service having the reservation logic injected it should work out of the box
• MonitorService need to take into consideration the cache reserved size
• org.opensearch.cluster.ClusterInfo::reservedSpace
• org.opensearch.cluster.InternalClusterInfoService::buildShardLevelInfo
• org.opensearch.index.store.StoreStats##reservedSize
  so that
  org.opensearch.cluster.routing.allocation.DiskThresholdMonitor
  and
  org.opensearch.cluster.routing.allocation.decider.DiskThresholdDecider
  take into consideration the new disk reservation logic

Reservation Logic

When creating the cache, a validations are needed to make sure:

• (cache defined reserved size - current cache phantom files + lucene indices file size) <= cluster.routing.allocation.disk.watermark.high and cluster.routing.allocation.disk.watermark.low and so on
• When cache is initiated on node start procedure, it's needed to walk through cache dir files and count their sizes
• For now we don't need to handle logic if cache data path has changed and old path has ghost files

Outcome of this

add fields reservedCacheSize and currentCacheSize to org.opensearch.env.NodeEnvironment.NodePath
and make these fields reflected correctly in org.opensearch.monitor.fs.FsProbe#getFSInfo to have semantic of
given Cache max reserved size, current cache occupied size, Implement size reservation logic to be reflected on NodesStats::FileSystemStats, Deciders, Monitoring Service