Remove adafruit_esp32spi_wifimanager import dependency

[brentru]

Removing

if isinstance(wifi_manager, adafruit_esp32spi_wifimanager.ESPSPI_WiFiManager):

in favor of

if ('ESPSPI_WiFiManager' in wifi_type or 'ESPAT_WiFiManager' in wifi_type):

The library won't need to import adafruit_esp32spi_wifimanager, and this'll add more flexibility for future types of WiFiManager classes (such as the ESPAT_WiFiManager @jerryneedell is working on. I've added support for that)

• also removing autodoc_mock_imports from sphinx configuration, required by adafruit_esp32spi_wifimanager's neopixel dependency

[jerryneedell]

looks great! tested with ESPAT_WiFiManager version under development

[brentru]

Thanks for testing @jerryneedell. Merging in