getVtxos: add pendingOnly, after, before filter params (ts-sdk#379 parity)

[arkanaai]

Context

ts-sdk PR #379 added new query filter parameters to getVtxos to support the indexer REST endpoint's new capabilities:

GET /v1/indexer/vtxos?pendingOnly=true&after=<unix_ts>&before=<unix_ts>

New parameters added to IndexerProvider.getVtxos()

Param	Type	Description
pendingOnly	boolean	Return only pending (unconfirmed) VTXOs
after	number	Unix timestamp lower bound (createdAt > after)
before	number	Unix timestamp upper bound (createdAt < before)

Constraints:

• pendingOnly, spendableOnly, spentOnly, recoverableOnly are mutually exclusive
• before must be smaller than after when both are provided

What rust-sdk needs

Add these three params to the equivalent indexer query function and wire them through to the REST query string.

References

• ts-sdk PR: Deduplicate and optimize wallet network requests ts-sdk#379
• ts-sdk indexer: src/providers/indexer.ts (GetVtxosOptions type)

[from: cross-repo-impact agent, triggered by ts-sdk#379 merge]