Improve buildscript to allow for custom selection of apps/watchfaces (#2429)

Author: Thulium-Drake

doc/buildWithDocker.md

@@ -87,3 +87,9 @@ Here's an example for `pinetime-app`:
 ```sh
 docker run --rm -it -v ${PWD}:/sources --user $(id -u):$(id -g) infinitime-build /opt/build.sh pinetime-app
 ```
+
+If you want to change the apps and/or watchfaces built in the project, you can pass `ENABLE_USERAPPS` and `ENABLE_WATCHFACES` as environment variables like so:
+
+```sh
+docker run --rm -it -v ${PWD}:/sources -e ENABLE_USERAPPS="Apps::Alarm,Apps::Timer,Apps::Steps,Apps::HeartRate,Apps::Music,Apps::Navigation" infinitime-build
+```

docker/build.sh

@@ -77,14 +77,19 @@ GetNrfSdk() {
 }
 
 CmakeGenerate() {
+  CMAKE_ARGS=()
+  [ -n "$ENABLE_USERAPPS" ]  && CMAKE_ARGS+=("-DENABLE_USERAPPS=$ENABLE_USERAPPS")
+  [ -n "$ENABLE_WATCHFACES" ] && CMAKE_ARGS+=("-DENABLE_WATCHFACES=$ENABLE_WATCHFACES")
+
   cmake -G "Unix Makefiles" \
     -S "$SOURCES_DIR" \
     -B "$BUILD_DIR" \
     -DCMAKE_BUILD_TYPE=$BUILD_TYPE \
     -DARM_NONE_EABI_TOOLCHAIN_PATH="$TOOLS_DIR/$GCC_ARM_PATH" \
     -DNRF5_SDK_PATH="$TOOLS_DIR/$NRF_SDK_VER" \
     -DBUILD_DFU=1 \
-    -DBUILD_RESOURCES=1
+    -DBUILD_RESOURCES=1 \
+    ${CMAKE_ARGS[@]}
 }
 
 CmakeBuild() {