Check ESP8285 at runtime

[mcspr]

resolves #7340

not really sure about isFlashInterfacePin(x), should there be isFlashInterfacePinEsp8285(x)?
main issue is every variant having #include "../generic/common.h"

[d-a-v]

Should we also change this one or leave it explicitly as statically defined esp8285 ?
In the latter case, should we disable dynamic detection when esp8285 is selected by user ?

[mcspr]

Should we also change this one or leave it explicitly as statically defined esp8285 ?
In the latter case, should we disable dynamic detection when esp8285 is selected by user ?

Either if we change board= to esp8285, right now it adds -DARDUINO_ESP8266_ESP01 when building with esp8285 as variant. Or, a custom flag inside of the variant header

And yes, there's no point in dynamic detection in the isFlashInterfacePin macro with specific variant.
Plus, only generic variant may add esp_is_8285() call, keeping the rest of variants with the original one.

[d-a-v]

Either if we change board= to esp8285, right now it adds -DARDUINO_ESP8266_ESP01 when building with esp8285 as variant. Or, a custom flag inside of the variant header

Given that esp_is_8285() is always defined, let's not introduce breaking changes by changing macros