data: Generate dash/app-grid defaults from text files

Defining default apps as serialized GVariants isn't very human-friendly,
which likely contributes to the fact that the lists are in parts horribly
outdated (Books! Cheese! Screenshot! gedit!).

Instead, generate the lists at build time from simple text files, which
should be much easier to update.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3632>

meson/generate-app-list.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+
+import argparse
+
+def read_app_ids(path) -> str:
+    ids = []
+    with open(path, "r") as file:
+        for line in file:
+            # strip comments
+            line, _, _ = line.partition('#');
+            line = line.strip()
+            if len(line) > 0:
+                ids.append(line)
+    return ids
+
+def print_as_array(ids):
+    mapped_ids = list(map(lambda i: f"  '{i}'", ids))
+    print('[')
+    print(',\n'.join(mapped_ids))
+    print(']')
+
+def print_as_pages(ids):
+    mapped_ids = []
+    for i, id in enumerate(ids):
+        mapped_ids.append(f"  '{id}': <{{'position': <{i}>}}>")
+
+    print('[{')
+    print(',\n'.join(mapped_ids))
+    print('}]')
+
+parser = argparse.ArgumentParser()
+parser.add_argument('--pages', action='store_true')
+parser.add_argument('file')
+args = parser.parse_args()
+
+ids = read_app_ids(args.file)
+if args.pages:
+    print_as_pages(ids)
+else:
+    print_as_array(ids)