Add Ctrl+Alt+P keybinding for Open PRT File

Bind opm-flow.openPrtFile to Ctrl+Alt+P (Cmd+Alt+P on Mac), active only
when an OPM Flow editor is focused, so the print file is reachable
without leaving the keyboard.

Author: magnesj

vscode-extension/package.json

@@ -170,6 +170,12 @@
         "key": "ctrl+/",
         "mac": "cmd+/",
         "when": "editorTextFocus && !editorReadonly && editorLangId == opm-flow"
+      },
+      {
+        "command": "opm-flow.openPrtFile",
+        "key": "ctrl+alt+p",
+        "mac": "cmd+alt+p",
+        "when": "editorLangId == opm-flow"
       }
     ],
     "configuration": {