[Keyboard] LeftyNumpad Keyboard (#10500)

* Clean LeftyNumpad code

* Fix typo in recently renamed file

* Fix issues with keymap layout

* Initial PR Feedback fixes

* Update keyboards/handwired/leftynumpad/config.h

Co-authored-by: Joel Challis <git@zvecr.com>

* Update keyboards/handwired/leftynumpad/config.h

Co-authored-by: Joel Challis <git@zvecr.com>

* Apply suggestions from code review

Co-authored-by: Joel Challis <git@zvecr.com>

* Apply suggestions from code review

Co-authored-by: James Young <18669334+noroadsleft@users.noreply.github.com>
Co-authored-by: Ryan <fauxpark@gmail.com>

* Add fixes based on PR feedback

* Update keyboards/handwired/leftynumpad/readme.md

Co-authored-by: Ryan <fauxpark@gmail.com>

Co-authored-by: Joel Challis <git@zvecr.com>
Co-authored-by: James Young <18669334+noroadsleft@users.noreply.github.com>
Co-authored-by: Ryan <fauxpark@gmail.com>

keyboards/handwired/leftynumpad/readme.md

@@ -0,0 +1,16 @@
+# LeftyNumpad
+
+![Image of LeftyNumpad](https://i.imgur.com/kkSPIxpl.png)
+
+A small numberpad/macropad intended to be placed southpaw-style on the left
+side of a keyboard.
+
+* Keyboard Maintainer: [Tom Swartz](https://github.com/tomswartz07)
+* Hardware Supported: Handwired, Uses Arudino Micro.
+* Hardware Availability: Handwired hardware.
+
+Make example for this keyboard (after setting up your build environment):
+
+    make handwired/leftynumpad:default
+
+See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).