Eliminate transpiling invalid in callfuncs

[TwitchBronBron]

Historically, callfuncs would fail if you didn't pass at least 1 argument (even if that argument was invalid). BrighterScript supported this by making the callfunc operator always inject an invalid as the first argument if you specified no arguments.

However, in recent years that problem seems to have been fixed in the Roku OS, so this feature is no longer necessary.

Actions:

• by default, do NOT inject the invalid as the first argument to callfunc operator statements.
• add a bsconfig option to re-enable this feature (for legacy purposes) since this can result in code not running properly.