feat: add ability to open files from Finder in macOS (neovide#2395)

* non-working plist attempt

* add Neovide.icns

* remove old build attempt

* make-icns script

* add background for dmg installer

* app + dmg builder script

* first version of Info.plist

* add missing keys from production build

* support retina backgrounds with tiff

* add lots of types...

* also add exported type declarations

* consistent quotes

* sigh

* comment

* feat(mac): implement openFiles on macOS

* feat: default to fork if in tty

* add source image and instructions

---------

Co-authored-by: Travis <[email protected]>

Author: polachok

Cargo.toml

@@ -131,4 +131,3 @@ long_description = """
 This is a simple graphical user interface for Neovim. Where possible there are some graphical improvements, but it should act functionally like the terminal UI.
 """
 osx_minimum_system_version = "10.11"
-

assets/dmg-background/README.md

@@ -0,0 +1,21 @@
+### OSX DMG Background
+
+source.pdf in this directory can be used for modifying the background of the
+dmg installer on OSX.
+
+JetBrainsMono can be downloaded from [Nerd Fonts](https://www.nerdfonts.com/font-downloads).
+
+After any changes, you must export 2 images with the following paths, filenames
+and dimensions:
+
+  1. `assets/neovide-dmg-background.png` (650x450)
+  2. `assets/[email protected]` (1300x900)
+
+Next, to support retina images you must generate a properly composed tiff by running the builder script from the root of the project:
+
+```
+macos-builder/make-icns
+```
+
+This script will also generate an `.icns` file with all the proper sizes from
+the `assets/neovide-1024.png` source image.