tools: Add clang-formatting tools

This adds two tools to the ./tools/ subdirectory:

== clang-formatter.sh ==

This is simply a small shell script that can be executed from the top of
the UHD repository, and it will format all files according the the
.clang-format file. It can be executed as such:

    $ CLANG_FORMAT=clang-format-14 ./tools/clang-formatter.sh apply

Specifying a clang-format executable is optional, but note that
clang-format 14.0 should be used.

== run-clang-format.py ==

This is a Python script that is a modified version from
https://github.com/gnuradio/clang-format-lint-action/blob/ \
    0b0cb14cf220a070d2a8b2610bd74ad1546252a1/run-clang-format.py

It was modified to add --patch-file option.

Alongside this file is a .clang-format-ignore file, which is sourced
from this script. The command can be run as such:

    $ ./tools/run-clang-format.py \
        --clang-format-executable clang-format-14 \
	--extensions c,cpp,h,hpp,hpp.in,ipp \
	-r \
	--patch-file format.patch \
	/path/to/uhd-repo

It will provide both a nice output summary as well as a patch file that
can be consumed with `patch -p0 < format.patch`.

.clang-format-ignore

@@ -0,0 +1,18 @@
+./host/cmake
+./host/lib/deps
+./mpm/lib/mykonos
+./mpm/lib/rfdc
+./mpm/include/mpm/rfdc
+./mpm/tools
+./fpga
+./tools
+./firmware
+*cdecode.*
+*getopt.*
+*_generated.h
+*template_lvbitx.*
+# Ignore all the junk
+.git
+.vscode
+./host/build
+.ccls-cache

tools/clang-formatter.sh

@@ -0,0 +1,48 @@
+#!/bin/bash
+
+cformat=${CLANG_FORMAT:-}
+if [ -z "$cformat" ]; then
+    cformat=$(which clang-format)
+fi
+
+_cmd=$1
+if [ -z "$_cmd" ]; then
+    _cmd="apply"
+fi
+
+cformat_args=""
+case $_cmd in
+    apply)
+        cformat_args="-i"
+        ;;
+    check)
+        cformat_args="-Werror --dry-run"
+        ;;
+    check_apply)
+        cformat_args="-Werror -i"
+        ;;
+    *)
+        echo "Usage: $0 [check|apply|check_apply]"
+esac
+
+find . \
+    -path './host/lib/deps' -prune -o \
+    -path './host/cmake' -prune -o \
+    -path './fpga' -prune -o \
+    -path './firmware' -prune -o \
+    -path './mpm/lib/mykonos' -prune -o \
+    -path './mpm/lib/rfdc' -prune -o \
+    -path './mpm/include/mpm/rfdc' -prune -o \
+    -path './mpm/tools' -prune -o \
+    -path './tools' -prune -o \
+    -name "getopt.*" -prune -o \
+    -name "cdecode.*" -prune -o \
+    -name "*_generated.h" -prune -o \
+    -name "*template_lvbitx.*" -prune -o \
+    -name "*.cpp" -print -o \
+    -name "*.hpp" -print -o \
+    -name "*.cpp.in" -print -o \
+    -name "*.hpp.in" -print -o \
+    -name "*.ipp" -print -o \
+    -name "*.c" -print -o \
+    -name "*.h" -print | xargs -n 10 -P 2 $cformat $cformat_args