feat: Add semaphore to limit concurrent basemaps import workflows BM-822

 (#157)

#### Description

Adds a semaphore to limit how many basemaps import workflows can run at
a time.

#### Intention

As we are about to bulk import the georeferenced historical imagery
surveys, it would be beneficial to add a semaphore to limit how many of
these can be run at once.

The limit of 10 is entirely arbitrary: very happy to change it to
whatever it seen as a better value before merging.

#### Checklist
- [ ] Tests updated
- [ ] Docs updated
- [x] Issue linked in Title

config/semaphores.yml

@@ -7,3 +7,4 @@ data:
   standardising: "2" # Limit of how many standardising workflow instances can run at the same time
   bulk: "4" # Limit of how many bulk workflow instances can run at the same time
   bulkcopy: "8" # Limit of how many publish-copy workflow instances can run at the same time
+  basemaps_import: "10" # Limit of how many basemaps import workflow instances can run at the same time

workflows/basemaps/imagery-import-cogify.yml

@@ -6,6 +6,11 @@ metadata:
 spec:
   parallelism: 100
   entrypoint: main
+  synchronization:
+    semaphore:
+      configMapKeyRef:
+        name: semaphores
+        key: basemaps_import
   templateDefaults:
     container:
       imagePullPolicy: Always