[FEATURE REQ]: Add user agent suffixing for additional client-level feature enablement flags.

[jeet1995]

See the reference PR to add additional user suffix context for below features (not exhaustive):

Hedging (not strictly clinet-level only - so, maybe bad idea)
ReadSessionRetryPolicy RemotePreferred
AnyApplicationPreferredRegion
DefaultDiagnosticsLogger used (not strictly clinet-level only - so, maybe bad idea)
ConnectionSharingEnabled
regionScopedSessionCapturingEnabled
any OperationPolicy used
isSessionCapturingOverrideEnabled
Any proactiveContainerInitConfig used
Any e2e policy specified (not strictly clinet-level only - so, maybe bad idea)

The constraint is to scope it to client-level enablement only.

Also see: #45197