Fix core::panic! not printing in examples (#153)

* fixes panic not showing in examples
removes panic_immediate_abort feature where present, renames config -> config.toml, enables panic-probe defmt printing feature and updates panic-probe to 0.2

* fix unintended changes in build_core and arch

* revert uninteded change

embassy-stm32-examples/Cargo.toml

@@ -46,7 +46,7 @@ defmt-rtt = "0.2.0"
 cortex-m = "0.7.1"
 cortex-m-rt = "0.6.13"
 embedded-hal    = { version = "0.2.4" }
-panic-probe = "0.1.0"
+panic-probe = { version = "0.2.0", features = ["print-defmt"] }
 futures = { version = "0.3.8", default-features = false, features = ["async-await"] }
 rtt-target = { version = "0.3", features = ["cortex-m"] }
 bxcan = "0.5.0"