Allow for per branch auto build

Triggered by a push ( ie. sync with master ), this code will check
to see if:

  - a variable exists called AUTO_BUILD_BRANCHES exists
  - said variable contains the branch

For example, if this workflow exists on the main branch, and
AUTO_BUILD_BRANCHES=main, the app will be auto-built and uploaded
to Testflight ...

If AUTO_BUILD_BRANCHES=dev though, the workflow will still be
triggered, but stop right at the start, at the Validate stage,
since the auto_build_check will return false.

This does not affect manual builds ... build process *if* the
branch is in the AUTO_BUILD_BRANCHES list *or* it a manual build.

Have tested as:

  - a manual build
  - a push where AUTO_BUILD_BRANCHES contains the branch
  - a push where AUTO_BUILD_BRANCHES doesn't contain the branch

.github/workflows/build_iAPS.yml

@@ -3,23 +3,47 @@ run-name: Build iAPS (${{ github.ref_name }})
 on:
   workflow_dispatch:
 
-  ## Remove the "#" sign from the beginning of the line below to get automated builds on push (code changes in your repository)
-  #push:
+  # this will trigger this workflow for any push to any branch that this workflow is
+  # active on, *but*, the auto_build_check job will check to see if this branch is
+  # enabled *for* being auto built, and short circuit the process if so.
+  #
+  # if AUTO_BUILD_BRANCHES is not set, or the current branch is not listed, this
+  # workflow is triggered, but doesn't actually do anything.
+  #
+  push:
 
-  schedule:
-    #- cron: '30 04 1 * *' # Runs at 04:30 UTC on the 1st every month
-    - cron: '0 8 * * 3' # Checks for updates at 08:00 UTC every Wednesday
-    - cron: '0 6 1 * *' # Builds the app on the 1st of every month at 06:00 UTC
-
 env:  
   UPSTREAM_REPO: Artificial-Pancreas/iAPS
   UPSTREAM_BRANCH: ${{ github.ref_name }} # branch on upstream repository to sync from (replace with specific branch name if needed)
   TARGET_BRANCH: ${{ github.ref_name }} # target branch on fork to be kept in sync, and target branch on upstream to be kept alive (replace with specific branch name if needed)
   ALIVE_BRANCH: alive
 
 jobs:
+  auto_build_check:
+    name: Check Auto Build Status
+    runs-on: ubuntu-latest
+    outputs:
+      AUTO_BUILD_ENABLED: ${{ steps.auto-build-enabled.outputs.auto_build }}
+
+    steps:
+      - name: Is Auto Build Branch
+        id: auto-build-enabled
+        run: |
+          echo "auto_build=false" >> $GITHUB_OUTPUT
+          if [ ! -z "${{ vars.AUTO_BUILD_BRANCHES }}" ]; then
+            if echo ",${{ vars.AUTO_BUILD_BRANCHES }}," | grep -q ",${{ github.ref_name }},"; then
+              echo "auto_build=true" >> $GITHUB_OUTPUT
+            fi
+          fi
+
+      - name: Show Auto Build Status
+        run: |
+          echo "Auto Build Status: ${{ steps.auto-build-enabled.outputs.auto_build }}"
+
   validate:
     name: Validate
+    needs: auto_build_check
+    if: needs.auto_build_check.outputs.AUTO_BUILD_ENABLED == 'true' || github.event_name == 'workflow_dispatch'
     uses: ./.github/workflows/validate_secrets.yml
     secrets: inherit
 
@@ -44,7 +68,7 @@ jobs:
         
         if [[ $PERMISSIONS =~ "workflow" || $PERMISSIONS == "" ]]; then
           echo "GH_PAT holds workflow permissions or is fine-grained PAT."
-          echo "has_permission=true" >> $GITHUB_OUTPUT # Set WORKFLOW_PERMISSION to false.
+          echo "has_permission=true" >> $GITHUB_OUTPUT # Set WORKFLOW_PERMISSION to true.
         else 
           echo "GH_PAT lacks workflow permissions."
           echo "Automated build features will be skipped!"
@@ -128,12 +152,6 @@ jobs:
     runs-on: macos-14
     permissions:
       contents: write
-    if: | # runs if started manually, or if sync schedule is set and enabled and scheduled on the first Saturday each month, or if sync schedule is set and enabled and new commits were found
-        github.event_name == 'workflow_dispatch' ||
-        (needs.check_alive_and_permissions.outputs.WORKFLOW_PERMISSION == 'true' &&
-          (vars.SCHEDULED_BUILD != 'false' && github.event.schedule == '0 6 1 * *') ||
-          (vars.SCHEDULED_SYNC == 'true' && needs.check_latest_from_upstream.outputs.NEW_COMMITS == 'true' )
-        )
     steps:
       - name: Set special variables
         run: |