feat(sdk-coin-sol): upgrade @solana/spl-token from 0.3.1 to 0.4.9

## Why this upgrade is needed

The current @solana/spl-token@0.3.1 has a broken ESM build - the .mjs
files have incorrect import paths that reference directories instead
of files (e.g., `./memoTransfer.mjs` instead of `./memoTransfer/index.mjs`).

This blocks webpack browser bundles from using ESM resolution for
@bitgo/sdk-coin-sol, which is required for @bitgo/wasm-solana support
(WASM modules need ESM for proper async initialization in browsers).

## What changed in 0.4.x

1. Fixed ESM imports - uses .js files with "type": "module" and
   correct paths like `./memoTransfer/index.js`

2. Removed SYSVAR_RENT_PUBKEY from Associated Token Account instructions.
   This is a valid Solana protocol change - the rent sysvar was deprecated
   because the Solana runtime now provides rent information automatically.
   Transactions are now more efficient (6 accounts instead of 7).

## Test fixture updates

27 test fixtures in test/resources/sol.ts were regenerated to reflect
the new transaction serialization. The transactions are functionally
equivalent and valid on-chain.

Ticket: BTC-3009

Author: lcovar

modules/sdk-coin-sol/package.json

@@ -45,7 +45,7 @@
     "@bitgo/sdk-lib-mpc": "^10.9.0",
     "@bitgo/statics": "^58.24.0",
     "@solana/spl-stake-pool": "1.1.8",
-    "@solana/spl-token": "0.3.1",
+    "@solana/spl-token": "0.4.9",
     "@solana/web3.js": "1.92.1",
     "bignumber.js": "^9.0.0",
     "bs58": "^4.0.1",