A common pattern pre-strict syntax was to mix config statements (assignments, blocks, includes) with imperative statements (if-else, try-catch, etc)

For example:

try {
    includeConfig 'http://example.com/nextflow.config'
}
catch( Exception e ) {
    // ...
}

In the v2 parser, I try to detect these patterns and provide a helpful error message: Try-catch blocks cannot be mixed with config statements, instead of a more cryptic syntax error

However, the above case currently yields Unexpected input: includeConfig. This is because the try block must be parsed as imperative code, which didn't account for using includeConfig as a regular function name.

This PR adds includeConfig as a valid identifier so that a better error message can be given here