Export tool : add space sanitizing

[Delphine-L]

I need to be able to sanitize the blank spaces in a file name before exporting it. Also, the sanitization of "/" was not working when providing a name for the dataset.
This PR adds the space sanitization and fix the "/" sanitization.

How to test the changes?

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. Create a file or a collection with spaces in the name
  2. Export using the "Sanitize spaces" option
  3. Verify the exported file contain underscores instead of spaces

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.