vim compiler plugin for ghostty filetype (#4645)

Basically integrates `ghostty +validate-config` with vim's compiler
feature. This allows validating the config from vim and navigating to
errors e.g. with the quickfix list.

build.zig

@@ -630,6 +630,7 @@ pub fn build(b: *std.Build) !void {
         _ = wf.add("syntax/ghostty.vim", config_vim.syntax);
         _ = wf.add("ftdetect/ghostty.vim", config_vim.ftdetect);
         _ = wf.add("ftplugin/ghostty.vim", config_vim.ftplugin);
+        _ = wf.add("compiler/ghostty.vim", config_vim.compiler);
         b.installDirectory(.{
             .source_dir = wf.getDirectory(),
             .install_dir = .prefix,
@@ -646,6 +647,7 @@ pub fn build(b: *std.Build) !void {
         _ = wf.add("syntax/ghostty.vim", config_vim.syntax);
         _ = wf.add("ftdetect/ghostty.vim", config_vim.ftdetect);
         _ = wf.add("ftplugin/ghostty.vim", config_vim.ftplugin);
+        _ = wf.add("compiler/ghostty.vim", config_vim.compiler);
         b.installDirectory(.{
             .source_dir = wf.getDirectory(),
             .install_dir = .prefix,

src/config/vim.zig

@@ -24,6 +24,21 @@ pub const ftplugin =
     \\
     \\let b:undo_ftplugin = 'setl cms< isk< ofu<'
     \\
+    \\if !exists('current_compiler')
+    \\  compiler ghostty
+    \\  let b:undo_ftplugin .= " makeprg< errorformat<"
+    \\endif
+    \\
+;
+pub const compiler =
+    \\if exists("current_compiler")
+    \\  finish
+    \\endif
+    \\let current_compiler = "ghostty"
+    \\
+    \\CompilerSet makeprg=ghostty\ +validate-config
+    \\CompilerSet errorformat=%f:%l:%m
+    \\
 ;
 
 /// Generates the syntax file at comptime.