fix: handle JS files when allowJs and checkJs options are set to true

[mkarajohn]

This pr allows the tool to handle JS files as well when the allowJs and checkJs are explicitly enabled in the user's config.

Resolves issues in the scenario when tsc-files runs as part of lint-staged over ts, tsx, js and jsx files.

If we do not handle JS files in this scenario, then they get passed along with the non-files arguments and we get the error about not being possible to mix -p along with files