feat(platform): Add Host-scoped credentials support for blocks HTTP requests (#10215)

Currently, we don't have a secure way to pass Authorization headers when
calling the `SendWebRequestBlock`.
This hinders the integration of third-party applications that do not yet
have native block support.

### Changes 🏗️

Add Host-scoped credentials support for the newly introduced
SendAuthenticatedWebRequestBlock.

<img width="1000" alt="image"
src="https://github.com/user-attachments/assets/0d3d577a-2b9b-4f0f-9377-0e00a069ba37"
/>
<img width="1000" alt="image"
src="https://github.com/user-attachments/assets/a59b9f16-c89c-453d-a628-1df0dfd60fb5"
/>

### Checklist 📋

#### For code changes:
- [x] I have clearly listed my changes in the PR description
- [x] I have made a test plan
- [x] I have tested my changes according to the test plan:
  <!-- Put your test plan here: -->
- [x] Uses `https://api.openai.com/v1/images/edits` through
SendWebRequestBlock by passing the api-key through host-scoped
credentials.

.github/workflows/platform-backend-ci.yml

@@ -190,9 +190,9 @@ jobs:
       - name: Run pytest with coverage
         run: |
           if [[ "${{ runner.debug }}" == "1" ]]; then
-            poetry run pytest -s -vv -o log_cli=true -o log_cli_level=DEBUG test
+            poetry run pytest -s -vv -o log_cli=true -o log_cli_level=DEBUG
           else
-            poetry run pytest -s -vv test
+            poetry run pytest -s -vv
           fi
         if: success() || (failure() && steps.lint.outcome == 'failure')
         env:
@@ -205,6 +205,7 @@ jobs:
           REDIS_HOST: "localhost"
           REDIS_PORT: "6379"
           REDIS_PASSWORD: "testpassword"
+          ENCRYPTION_KEY: "dvziYgz0KSK8FENhju0ZYi8-fRTfAdlz6YLhdB_jhNw=" # DO NOT USE IN PRODUCTION!!
 
     env:
       CI: true