[Keymap] VIA keymap for the Sofle (#10446)

* Added via support

* Now uses LTO_ENABLE

* Deactivated console to save space

* Update keyboards/sofle/keymaps/via/readme.md

* Added GPL license

* Update keyboards/sofle/keymaps/via/keymap.c

* Update keyboards/sofle/keymaps/via/keymap.c

* Update keyboards/sofle/keymaps/via/keymap.c

* Update keyboards/sofle/keymaps/via/keymap.c

keyboards/sofle/keymaps/via/readme.md

@@ -0,0 +1,14 @@
+# VIA keymap for Sofle
+
+Layout in [Keyboard Layout Editor](http://www.keyboard-layout-editor.com/#/gists/76efb423a46cbbea75465cb468eef7ff) and [adjust layer](http://www.keyboard-layout-editor.com/#/gists/4bcf66f922cfd54da20ba04905d56bd4)
+
+
+Features:
+
+- Symmetric modifiers (CMD/Super, Alt/Opt, Ctrl, Shift)
+- Modes for Qwerty and Colemak support
+- The OLED on master half shows selected mode and caps lock state and is rotated.
+- Left encoder controls volume up/down/mute. Right encoder PGUP/PGDOWN.
+- Via support
+- RGB underglow support
+