boards: wch: update the bord test definitions to match the new drivers

The CH32V series now has GPIO, watchdog, I2C, and PWM drivers. Enable
Twister for these drivers by updating the board definitions to match.

On the larger chips, also enable the watchdog in Devicetree so it's
usable by the sample.

Note that the 203 and 303 do not yet have the appropriate iwdg
Devicetree node.

Signed-off-by: Michael Hope <michaelh@juju.nz>