cmake: Apply cmake-format

This commit adds `.cmake-format.py`. It is mostly inspired by the GNU Radio
version of it.

Steps to reproduce these results:
- `pip3 install cmakelang`
- `cmake-format --dump-config python > .cmake-format.py`
- Modify .cmake-format.py to be close to the GNU Radio version.
- `cmake-format -c .cmake-format.py -i $(git ls-files | grep CMakeLists.txt) $(git ls-files | grep .cmake)`

Fixes gnuradio#600
Fixes gnuradio#423

Signed-off-by: Johannes Demel <[email protected]>

.cmake-format.py

@@ -0,0 +1,69 @@
+# Copyright 2023 Johannes Demel
+# SPDX-License-Identifier: LGPL-3.0-or-later
+
+# ----------------------------------
+# Options affecting listfile parsing
+# ----------------------------------
+with section("parse"):
+    additional_commands = {
+        "gr_python_install": {
+            "flags": [],
+            "kwargs": {"PROGRAMS": "*", "FILES": "*", "DESTINATION": "*"},
+        },
+    }
+
+
+with section("format"):
+    # Disable formatting entirely, making cmake-format a no-op
+    disable = False
+
+    # How wide to allow formatted cmake files
+    line_width = 80
+
+    # How many spaces to tab for indent
+    tab_size = 2
+
+    # If true, lines are indented using tab characters (utf-8 0x09) instead of
+    # <tab_size> space characters (utf-8 0x20). In cases where the layout would
+    # require a fractional tab character, the behavior of the  fractional
+    # indentation is governed by <fractional_tab_policy>
+    use_tabchars = False
+
+    # If true, separate flow control names from their parentheses with a space
+    separate_ctrl_name_with_space = False
+
+    # If true, separate function names from parentheses with a space
+    separate_fn_name_with_space = False
+
+    # If a statement is wrapped to more than one line, than dangle the closing
+    # parenthesis on its own line.
+    dangle_parens = False
+
+    # If the statement spelling length (including space and parenthesis) is
+    # smaller than this amount, then force reject nested layouts.
+    min_prefix_chars = tab_size
+
+    # If the statement spelling length (including space and parenthesis) is larger
+    # than the tab width by more than this amount, then force reject un-nested
+    # layouts.
+    max_prefix_chars = 3 * tab_size
+
+    # What style line endings to use in the output.
+    line_ending = "unix"
+
+    # Format command names consistently as 'lower' or 'upper' case
+    command_case = "canonical"
+
+    # Format keywords consistently as 'lower' or 'upper' case
+    keyword_case = "upper"
+
+
+with section("markup"):
+    first_comment_is_literal = True
+    enable_markup = False
+
+
+with section("lint"):
+    max_arguments = 6
+    max_localvars = 20
+    max_statements = 75