Added Kakoune hook to compile LaTeX on save.

Added Kakoune settings to disable removing trailing indentation and enable highlighting it.

programs/kakoune.nix

@@ -9,11 +9,10 @@
     };
     hooks = [
       {
+        # When the filetype=latex option is set in a buffer context (automatically), add a new hook to build the latex file on write
         name = "BufSetOption";
         option = "filetype=latex";
-        commands = ''
-          set-option buffer makecmd latexmk -pvc -pdf -e '$pdf_previewer="xdg-open %S"' -e '$pdflatex="pdflatex -interaction=nonstopmode -synctex=1 %O %S"' %opt{documentsrc}
-        '';
+        commands = "hook buffer BufWritePost .* %{ texlab-build }";
       }
     ];
     keyMappings = [
@@ -36,6 +35,12 @@
     ];
   };
   extraConfig = ''
+    # highlight trailing whitespace
+    add-highlighter global/trailing-whitespace regex '\h+$' 0:Error
+
+    # don't remove trailing indent
+    set global disabled_hooks .*-trim-indent
+
     eval %sh{kak-lsp --kakoune -s $kak_session}
     lsp-enable
   '';