Binary Provisioning: improve script syntax error reporting during dependency analysis

[pablochacin]

When running a test with syntax errors, the dependency analysis fails, but the error message received by the user may be confusing because it refers to the automatic dependency resolution.

cat <<EOF | k6 run - 
export default function() {
          console.log('hello world'
}
> EOF
ERRO[0000] Automatic extension resolution is enabled but it failed to analyze the dependencies. Please, make sure to report this issue by opening a bug report.  error="-:3:2 Expected \")\" but found \"}\""
ERRO[0000] -:3:2 Expected ")" but found "}"

With the automatic extension resolution disabled, the error message is:

ERRO[0000] GoError: file:///-: Line 3:3 Unexpected token } (and 1 more errors)  hint="script exception

It would be preferable the error message were more specific to the root cause.