File without extension fails upload

Thanks for the issue and MR @greenSkin!

The merge request code doesn't raise any red flags to me, so I'll look at testing this out and if I can confirm the original bug and the fix, we'll go ahead and merge it. Might be a good case for the first actual tests for the module too (if only to satisfy my desire to write some). I appreciate this, as soon as I have a a little time to look at this more in depth I will.

@greenSkin I tried to replicate this issue this weekend with a file named `apple-developer-merchantid-domain-association` and I had no issues uploading said file with no extension. Are you able to replicate this issue on a site with no additional modules or filesystem config/restrictions? While I do want to ensure the functionality works with the widest range of supported configurations, I want to be able to replicate the initial issue before merging a fix for it.

We are on Drupal 10.2 and don't believe we are using any module that affects file extension validation, but I'll spin up a clean install and see if I can reproduce the issue.

Note however that "file_validate_extensions" is deprecated and will be removed in Drupal 11. Maybe this is worth a D10+ release?

@greenSkin looking ahead for deprecations does sound like a good idea. Are you able to send me the API doc that specifies this new method? I just saw this deprecation notice so I see that is what you're referring to. I just can't locate the documentation how this is supposed to work. The file that gets downloaded from stripe has no extension by default, so however we configure this, I think that is the use care we should support.

Sorry for the late reply on this, I must have missed the notification in my inbox.

Nevermind, the API docs refer to this: https://www.drupal.org/node/3363700 →

That looks like exactly what you have here

@greenSkin I had some time to come back and think about this more, I read some Drupal core issues and did some interweb searching, and came across this: https://drupal.stackexchange.com/questions/87146/upload-text-file-withou...

I think what we really want is just to ensure the file uploaded is a text file, and maybe confirm it's size isn't enormous, and then we can just remove the extension check altogether because by default, this file will have no extension. I also don't recall if I included a permission in the module, but we probably want to have an explicit permission for accessing this form that is only given to trusted users.

I think I'll look at adding a validator plugin that does what we want (only text, file not huge) and then add that. What do you think?