feat(statics): add CoinFeature.STAKING to txdc coin features

Enable staking feature for txdc (testnet XDC) so WalletPlatform and
bitgo-ui can identify XDC testnet as staking-capable. The mainnet xdc
coin is intentionally left unchanged pending full go-live.

Ticket: SC-5664

Author: Doddanna17

modules/statics/src/allCoinsAndTokens.ts

@@ -1538,7 +1538,7 @@ export const allCoinsAndTokens = [
     18,
     UnderlyingAsset.XDC,
     BaseUnit.ETH,
-    XDC_FEATURES
+    [...XDC_FEATURES, CoinFeature.STAKING]
   ),
   account(
     '297edf01-b166-45fb-be6f-da6680635f72',