Add option to ignore untracked files in unstaged changes panel

[rht]

Is your feature request related to a problem? Please describe.
I'm a tig user evaluating alternatives. In tig, by default, only unstaged tracked files are shown in the view. With gitui, it's rather noisy. I have files like benchmark/profile log output that I produce quickly, and usually don't bother to add into .gitignore.

Describe the solution you'd like
Would be nice if there is a config option for this.

[kosayoda]

Tangentially related, since currently there is no way to tell the application to not show untracked files by default, you have two options:

1. Set status.ShowUntrackedFiles in your system, global, or local Git Configuration.
2. Manually set the app to not show untracked files each time you launch it: Open the options menu (key is o by default), then change Show untracked to No

[extrawurst]

@kosayoda that’s exactly the status quo. Storing your options per repo is something we will eventually add

[stale]

This issue has been automatically marked as stale because it has not had any activity half a year. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.

[extrawurst]

Storing these options per repo is implemented on master