[Keyboard] Add support for Southpaw Extended 65% (#8465)

* Add support for Southpaw Extended 65%

* Update keyboards/switchplate/southpaw_65/readme.md

* Update keyboards/switchplate/southpaw_65/readme.md

* Update keyboards/switchplate/southpaw_65/readme.md

* Update keyboards/switchplate/southpaw_65/southpaw_65.c

* Update keyboards/switchplate/southpaw_65/rules.mk

* Cleaned up keymaps
-Removed default2 keymap
-Removed default_iso2 keymap
-Rename default keymap directory to default_ansi to reflect correct keymap name

* Update readme.md for default_ansi keymap directory change

* Add layout_all for configurator and correct maximum number of keys supported in readme.md

* Update keyboards/switchplate/southpaw_65/info.json

Forgot to change name to LAYOUT_all

* Update keyboards/switchplate/southpaw_65/info.json

* Update keyboards/switchplate/southpaw_65/readme.md

* Update keyboards/switchplate/southpaw_65/rules.mk

* Add LAYOUT_all keymap

* Update keyboards/switchplate/southpaw_65/keymaps/default/keymap.c

* Update keyboards/switchplate/southpaw_65/info.json

keyboards/switchplate/southpaw_65/readme.md

@@ -0,0 +1,23 @@
+# Southpaw Extended 65%
+
+![Southpaw Extended 65%](https://i.imgur.com/9HSWmmll.jpg)
+
+Left Hand Number Pad Keyboard with 85 Keys & RGB LED Underglow
+- Designed by Reconsiderit
+- Up to 91 keys
+- iso and ansi support
+- Uses Kimera core
+
+* Keyboard Maintainer: QMK Community
+* Hardware Supported: Southpaw Extended 65%
+* Hardware Availability: [Geekhack GB Thread](https://geekhack.org/index.php?topic=92344.0)
+
+Make example for this keyboard (after setting up your build environment):
+
+    make switchplate/southpaw_65:default_ansi
+
+Install examples:
+
+    make switchplate/southpaw_65:default_ansi:flash
+
+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).