Use 'extends' for STM32F1

[sjasonsmith]

Description

Utilize extends in PlatformIO to extract the commonalities between all STM32F1 environments.

Visual Studio Code doesn't properly recognize environments if their platform is included as part of an extends variable. For this reason I have left platform in each environment even though PlatformIO does not require it.

This PR overlaps with another PR of mine: #18089.
If this PR is merged then #18089 is not necessary.

Benefits

Allows STM32F1-specific changes to be made in one place and apply to all environments.
In this changelist, the only real change is reducing the version of the Adafruit MAX31865 library, since version 1.2 is incompatible with the STM32F1 HAL.

Related Issues

#18081

[sjasonsmith]

I am currently printing on an SKR Mini E3 1.0 built using these changes from inside VS Code.

[sjasonsmith]

I've updated this to use a dynamic variable for the platform name, rather than redefining ststm32 in every environment. This way we satisfy VS Code's need for every environment to contain a platform entry, while still allowing it to be overridden from one place.

[thinkyhead]

Unfortunately, last I checked with PlatformIO, the VSCode extension still doesn't know what to do with extends and it won't display any environment that includes it in the Tasks list. That's why I have not re-applied extends yet since I first tried it in December.

[thinkyhead]

Just checked, and the PlatformIO extension still hasn't been updated since November. So we have to wait for that to happen before we can enjoy the benefits of extends.

[sjasonsmith]

Unfortunately, last I checked with PlatformIO, the VSCode extension still doesn't know what to do with extends and it won't display any environment that includes it in the Tasks list. That's why I have not re-applied extends yet since I first tried it in December.

@thinkyhead, it shows them as long as you define platform in each environment. If you comment out platform they disappear as you describe.

[thinkyhead]

Oh, that's interesting. I wonder why that matters.