feat(platform): Support multiple credentials inputs on blocks (#8932)

- Resolves #8930
- Depends on #8725

### Changes 🏗️

- feat(platform): Support multiple credentials inputs on blocks

Aside from `credentials`, fields within the name pattern `*_credentials`
are now also supported!

- Update docs with info on multi credentials support

### 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:
  - [x] Ask @aarushik93 to test

docs/content/platform/new_blocks.md

@@ -238,6 +238,16 @@ Naturally, to add an authenticated block for a new provider, you'll have to add
 ```
 </details>
 
+#### Multiple credentials inputs
+Multiple credentials inputs are supported, under the following conditions:
+- The name of each of the credentials input fields must end with `_credentials`.
+- The names of the credentials input fields must match the names of the corresponding
+  parameters on the `run(..)` method of the block.
+- If more than one of the credentials parameters are required, `test_credentials`
+  is a `dict[str, Credentials]`, with for each required credentials input the
+  parameter name as the key and suitable test credentials as the value.
+
+
 #### Adding an OAuth2 service integration
 
 To add support for a new OAuth2-authenticated service, you'll need to add an `OAuthHandler`.