[Writable Warm] File Pinning support and TTL based eviction for FileCache

[rayshrey]

Is your feature request related to a problem? Please describe

With FileCache now being used by Composite Directory in addition to Remote Snapshots we need to add additional functionalities. A few examples below:

• Pinning a certain file so that it is safe from eviction
• More eviction strategies such as ttl based eviction (currently we only have overflow based eviction)

Describe the solution you'd like

File pinning and ttl based eviction should work.
Will update this section with more details once have a concrete LLD for this.

Related component

Storage:Remote

Describe alternatives you've considered

No response

Additional context

No response

[peternied]

[Triage - attendees 1 2 3 4 5 6 7 8]
@rayshrey Thanks for creating this issue.