Change split_common to use RGBLIGHT_SPLIT (#5509)

Change split_common to use RGBLIGHT_SPLIT (#5509)

* add I2C_slave_buffer_t to quantum/split_common/transport.c

Improvements to ease the maintenance of the I2C slave buffer layout. And this commit does not change the compilation results.

* add temporary pdhelix(Patched Helix) code

* temporary cherry-pick from #5020

add new version(#5020) quantum/rgblight.[ch], quantum/rgblight_modes.h

* add post_config.h support to build_keyboard.mk

* add quantum/rgblight_post_config.h, quantum/split_common/post_config.h

Add quantum/rgblight_post_config.h and quantum/split_common/post_config.h using POST_CONFIG_H variable of build_keyboard.mk.

quantum/rgblight_post_config.h additionally defines RGBLIGHT_SPLIT if RGBLED_SPIT is defined.

quantum/split_common/post_config.h defines RGBLIGHT_SPLIT additionally when master-slave communication is I2C.

* Change split_common's transport.c I2C to use the synchronization feature of rgblight.c

* Change split_common's transport.c serial to use the synchronization feature of rgblight.c

* test RGBLIGHT_SPLIT on keyboards/handwired/pdhelix

* Test End Revert "test RGBLIGHT_SPLIT on keyboards/handwired/pdhelix"

This reverts commit 80118a6bbd3d9fc4c7797fef0c34bc67aa73aa98.

[x] make RGBLIGHT_TEST=1 handwired/pdhelix/i2c:default
[x] make RGBLIGHT_TEST=2 handwired/pdhelix/i2c:default (same RGBLIGHT_TEST=3)
[x] make RGBLIGHT_TEST=3 handwired/pdhelix/i2c:default

[x] make RGBLIGHT_TEST=1 handwired/pdhelix/pd2:default
[x] make RGBLIGHT_TEST=2 handwired/pdhelix/pd2:default
[x] make RGBLIGHT_TEST=3 handwired/pdhelix/pd2:default

[x] make RGBLIGHT_TEST=1 handwired/pdhelix/pd2_2oled:default
[x] make RGBLIGHT_TEST=2 handwired/pdhelix/pd2_2oled:default
[x] make RGBLIGHT_TEST=3 handwired/pdhelix/pd2_2oled:default

* Test End, Revert "temporary cherry-pick from #5020"

This reverts commit d35069f68bda0c50370442a5c7aae60c2f4ce5c0.

* Test End, Revert "add temporary pdhelix(Patched Helix) code"

This reverts commit aebddfc1a879796afae297ef0723a4fe73af3660.

* temporarily cherry-pick from #5020 to see if it passes the travis-ci test.

add new version(#5020) quantum/rgblight.[ch], quantum/rgblight_modes.h

* Passed the travis-ci test. Revert "temporarily cherry-pick from #5020 to see if it passes the travis-ci test."

This reverts commit 647c0a9755eb6a05f76d09b2d59bce67b85a841f.

* update docs/config_options.md

* update split_common/transport.c, improves maintainability of serial transaction IDs.

No change in build result.

* temporary cherry-pick from #5020

* fix build fail keebio/iris/rev3:default

* fix build fail lets_split_eh/eh:default

* Revert "temporary cherry-pick from #5020"

This reverts commit be48ca1b4515366a097af8dd1cd7b28b7ee09947.

* temporary cherry-pick from #5020 (0.6.336)

* Revert "temporary cherry-pick from #5020 (0.6.336)"

This reverts commit 978d26a8b3cf0acc485838a7d76d6128b77c630c.

* temporary cherry-pick from #5020 (0.6.336)