Add helix-specific ignore files

[PaulOlteanu]

Fixes #7423

I chose .hxignore as the file name to match other tools such as ripgrep's .rgignore, but this is open to suggestions

[poliorcetics]

I would much prefer .helix/ignore for two reasons:

1. We could have one in the global config directory that always apply, making it easy to ignore common but useless files
2. It would integrate with the existing .helix machinery, making less clutter (there is now .helix and .hxignore, when it already should always be .config/hx/...)

[pascalkuthe]

I think you could add the gloabl ignore file (see #8300) right in this PR too, so we can get this done in one go

[meepleek]

I think you could add the gloabl ignore file (see #8300) right in this PR too, so we can get this done in one go

I thought these were orthogonal, so I created a new PR for the global file. Either way I'll be happy. Should I close #8300 then?

[gamma-delta]

Hello, just like to add my two cents here -- I'm using Helix as my editor for C# in Godot and the ability to mask out all the .import and .tscn files and so on would be amazing, especially because for LSP reasons I need to have Helix's origin directory be the root of the project. :)

[David-Else]

@PaulOlteanu Hi, I have read the docs at https://docs.helix-editor.com/master/configuration.html?highlight=ignore#editorfile-picker-section, and it mentions a .ignore file, but if I want a global ignore file in my config dir then I need to use a ignore file, am i misunderstanding something or is this some kind of error? There seems to be no mention in the docs of a ignore file, and a .ignore file works in my local directory. Should the global ignore file not also have a . in front of it?

[the-mikedavis]

It looks like we don't document these new files anywhere yet. That section in the docs could mention that you can use ignore files with a local .ignore, ~/.ignore or now .helix/ignore and ~/.config/helix/ignore