[devtools/x] Add `errmap` extension to ignored whitespace file extensions
[devtools/x] Add `errmap` extension to ignored whitespace file extensions

Exclude files with the `errmap` file extension from having whitespace lints
run on them.

Closes: #5577

aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,libra/libra,libra/libra,aptos-labs/aptos-core,libra/libra