[CI]: Set up CI for STM32WLx (CI_BUILD_ALL)

This adds a build for the Nucleo WL55JC1 board, and ensures that
the STM32WLx examples are skipped on all other boards.

To slightly generalize the list of boards, this pushes the pnum option
for the black pill into the boards list, instead of setting it into the
options variable (even though it is technically a board option and not
the board itself, conceptually it is part of the selected board and
these values are just concatenated, so it can go in either place).

Co-Authored-By: jgromes <jan.gromes@gmail.com>

.github/workflows/main.yml

@@ -27,7 +27,8 @@ jobs:
           - esp8266:esp8266:generic
           - Intel:arc32:arduino_101
           - SparkFun:apollo3:sfe_artemis
-          - STMicroelectronics:stm32:GenF3
+          - STMicroelectronics:stm32:GenF3:pnum=BLACKPILL_F303CC
+          - STMicroelectronics:stm32:Nucleo_64:pnum=NUCLEO_WL55JC1
           - stm32duino:STM32F1:mapleMini
           - MegaCoreX:megaavr:4809
           - arduino:mbed_rp2040:pico
@@ -63,9 +64,9 @@ jobs:
         id: prep
         run:
           |
-          # common settings - no extra options, skip nothing, all warnings
+          # common settings - no extra options, skip STM32WL examples, all warnings
           echo "::set-output name=options::"
-          echo "::set-output name=skip-pattern::''"
+          echo "::set-output name=skip-pattern::'STM32WL'"
           echo "::set-output name=warnings::'all'"
 
           # platform-dependent settings - extra board options, board index URLs, skip patterns etc.
@@ -109,9 +110,13 @@ jobs:
 
           elif [[ "${{ contains(matrix.board, 'STMicroelectronics:stm32') }}" == "true" ]]; then
             # STM32 (official core)
-            echo "::set-output name=options:::pnum=BLACKPILL_F303CC"
             echo "::set-output name=index-url::--additional-urls https://raw.githubusercontent.com/stm32duino/BoardManagerFiles/main/package_stmicroelectronics_index.json"
 
+            if [[ "${{ contains(matrix.board, 'NUCLEO_WL55') }}" == "true" ]]; then
+              # Do *not* skip STM32WL examples
+              echo "::set-output name=skip-pattern::''"
+            fi
+
           elif [[ "${{ contains(matrix.board, 'stm32duino:STM32F1') }}" == "true" ]]; then
             # STM32 (unofficial core)
             echo "::set-output name=options:::bootloader_version=original,cpu_speed=speed_72mhz"