Add option to disable batch mode for all tools

Summary of Changes

This pr adds a configuration option to disable batch mode entirely for tools. The option is disable_batch_input in galaxy.yml and "true" will make it so that for single dataset inputs, both modes ("multiple datasets" and "dataset collections" that cause Galaxy to treat it as a batch job will be removed from the interface. This does not affect any input types that are not treated as batches such as the "Multiple Dataset" (soon to be "Dataset(s)") that is separate from single dataset inputs. I kept the icon for visual purposes, as well as the browser button beside it for convenience.

Checklist

• The MR has a clear and concise title
• Code is self-documented and follows style guidelines.
• Automated tests are written and pass successfully.
• Regression tests (e.g. manually triggered system tests, manual GUI/tool tests, ...) are performed to make sure the MR does not break anything (when applicable)
• Readme file is present and up-to-date.

Documentation Updates

Additional Notes

Closes #127 (closed)