test: Pass bench exe into test framework utils

This teaches the test framework about the bench executable, which is
required for the next commit.

.github/workflows/ci.yml

@@ -320,6 +320,7 @@ jobs:
           BITCOIN_BIN: '${{ github.workspace }}\build\bin\Release\bitcoin.exe'
           BITCOIND: '${{ github.workspace }}\build\bin\Release\bitcoind.exe'
           BITCOINCLI: '${{ github.workspace }}\build\bin\Release\bitcoin-cli.exe'
+          BITCOIN_BENCH: '${{ github.workspace }}\build\bin\Release\bench_bitcoin.exe'
           BITCOINTX: '${{ github.workspace }}\build\bin\Release\bitcoin-tx.exe'
           BITCOINUTIL: '${{ github.workspace }}\build\bin\Release\bitcoin-util.exe'
           BITCOINWALLET: '${{ github.workspace }}\build\bin\Release\bitcoin-wallet.exe'