Add Keychron C3 Pro (Red & RGB) (#24874)

* Add Keychron C3 Pro variants

* Update to upstream standards

* Apply suggestions from code review

Co-authored-by: jack <0x6a73@protonmail.com>
Co-authored-by: Ryan <fauxpark@gmail.com>

* Reformatted `keyboard.json` for `red`/`rgb` and `c3_pro.c`

* Apply suggestions from code review

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

* Update keyboards/keychron/c3_pro/ansi/red/config.h

Co-authored-by: Daniel <1767914+iamdanielv@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Drashna Jaelre <drashna@live.com>

* Add C Pro V2 variants

* remove boards by accident

---------

Co-authored-by: jack <0x6a73@protonmail.com>
Co-authored-by: Ryan <fauxpark@gmail.com>
Co-authored-by: Daniel <1767914+iamdanielv@users.noreply.github.com>
Co-authored-by: Drashna Jaelre <drashna@live.com>

keyboards/keychron/c3_pro/config.h

@@ -0,0 +1,24 @@
+/* Copyright 2024 @ Keychron(https://www.keychron.com)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+/* I2C driver Configuration */
+#define I2C1_SCL_PIN B8
+#define I2C1_SDA_PIN B9
+#define I2C1_CLOCK_SPEED 400000
+#define I2C1_DUTY_CYCLE FAST_DUTY_CYCLE_2
+