* modify oled_driver to support SH1106
also:
- improve mechanism to specify which OLED IC we use
- comment calc_bounds()
- give OLED_COLUMN_OFFSET a default value
- inline comment re: OLED MEMORY_MODE and SH1106
- update docs/feature_oled_driver.h for SH1106 support and related changes
- docs: OLED: note we have tested SSD1306 on ARM boards (per @XScorpion2)
- define out MEMORY_MODE when using SH1106 OLED driver
* document that SSD1306 128x64 on AVR works
Per @XScorpion2: https://github.com/qmk/qmk_firmware/pull/5787#discussion_r291837842
