ci: use diff command for QA URL comments BM-1461 (#1441)

### Motivation

When a user modifies tilesets via a pull request, our `build.yml`
workflow automatically generates a pull request comment containing QA
URLs for the affected tilesets. This allows reviewers to easily examine
the imagery.

At the moment, our QA URLs are broken for tilesets that describe
pipelines. Such as our **`elevation`** tileset.

Currently, our `import` command produces the QA URL comments. In this
[pull request], we introduce a new `diff` command, which fixes the QA
URL issues.

[pull request]: linz/basemaps#3555

### Note

We still need the `import` command for handling the DynamoDB operations.
We need only switch over to the `diff` command for the QA URL comments.

### Modifications

- **.github/workflows/build.yml**

- Updated the **`Compare to Production`** step to use the new `diff` CLI
command.

### Verification

See this comment
[here](#1441 (comment)).

Author: tawera-manaena

.github/workflows/build.yml

@@ -89,7 +89,7 @@ jobs:
       - name: Compare To Production
         run: |
           aws s3 cp s3://linz-basemaps/config/config-latest.json.gz .
-          ./scripts/bmc.sh ./index.cjs config import --config ${CONFIG_LOCATION_STAGING} --output $PWD/changes.md --target $PWD/config-latest.json.gz
+          ./scripts/bmc.sh ./index.cjs config diff --before $PWD/config-latest.json.gz --after ${CONFIG_LOCATION_STAGING} --output $PWD/changes.md
 
       - name: Upload changes.md as artifact (if oversized)
         if: github.ref != 'refs/heads/master' && github.event_name == 'pull_request' && (hashFiles('changes.md') != '')