Following up on #3231

Keep "astyled" reformatting

- `SD_DETECT_PIN` replaces `SDCARDDETECT`
- `SD_DETECT_INVERTED` replaces `SDCARDDETECTINVERTED`
- Revise the description of `SD_DETECT_INVERTED`
- Add a note about the override of `SD_DETECT_INVERTED` in
`Conditionals.h`

- Rename the pin so it can be tested with `PIN_EXISTS`
- Fix some incorrect tests for `SDCARDDETECT`

For consistency with other pins, allowing use of `PIN_EXISTS` macro.

Apply `ENABLED` / `DISABLED` / `HAS_SERVOS` macros to pins files.

- Change suggested at
https://github.com/MarlinFirmware/Marlin/issues/2482#issuecomment-123553
266

- create sled pin definition
- G28 Works with sled

Hopefully this is helpful to organization and future expansion….

Hopefully this is helpful to organization and future expansion….

Hopefully this is helpful to organization and future expansion….