* update keyboards/helix/rev2/local_features.mk - Improved parsing of the `HELIX =` option
* add 'is_mac_mode()' into keyboards/helix/rev2/rev2.c
* update helix/rev2/keymaps/default/keymap.c: use rgblight query functions
* Makes the OLED driver used by the helix:default keymap switchable.
* use TOP/drivers/oled/oled_driver.c
`make helix:default`
or
`make OLED_SELECT=core helix:default`
* use helix/local_drivers/ssd1306.c
`make OLED_SELECT=local helix:default`
* Separated the OLED related code from keymap.c and moved it to oled_display.c.
* Change the 'led_test' keymap to follow the changes in the 'default' keymap.
* update helix/rev2/keymaps/default/oled_display.c
* add '#define OLED_UPDATE_INTERVAL 50' into keyboards/helix/rev2/config.h
* Support for OLED_UPDATE_INTERVAL, even for older types of OLED tasks
* add readme.md for helix/rev2
* Apply drashna's suggestions to rev2.c.
* Apply drashna's suggestions to rev3_4rows.c, rev3_5rows.c.
Co-authored-by: mtei <2170248+mtei@users.noreply.github.com>
