feat: export network parseDescriptor from babylon namespace

The ESM build support added in PR #7534 introduced strict `exports` in
package.json which blocks deep imports like:
- @bitgo/utxo-staking/dist/src/babylon/parseDescriptor
- @bitgo/utxo-staking/dist/src/babylon/network

This breaks consumers (e.g., wallet-platform) that rely on these internal
modules. By re-exporting them from the babylon namespace, consumers can
import via the public API:

  import { babylon } from '@bitgo/utxo-staking';
  const { parseStakingDescriptor, toBitcoinJsNetwork } = babylon;

Ticket: BTC-2826

TICKET: BTC-2826

Author: lcovar

modules/utxo-staking/src/babylon/index.ts

@@ -7,6 +7,8 @@ bitcoinjslib.initEccLib(utxolib.ecc);
 
 export * from './delegationMessage';
 export * from './descriptor';
+export * from './network';
+export * from './parseDescriptor';
 export * from './stakingParams';
 export * from './stakingManager';
 export * from './undelegation';