Streamline and refactor the azure and the azure-web adapters.

- Add SCF/Azure Gradle sample and docs.
- Move the function-azure-di-samples into standalone projects.
 - Apply the name convetion and project structure for the SCF adaptes.
   E.g.  function-sample-azure-XXX projects under the spring-cloud-function-samples root.
 - Remove the redudant samples.
 - Improve the samples docs and the Adapter generic docs.
- Streamline docs.
- Add azure web adapter sample and README.
- Add Spring Azure Functions banner for azure and azure web adapters.
- azure-web adapter fixes:
  - Fix issues in serverles-web ProxyHttpServletResponse implementation.
  - Remove the custom FunctionClassUtils utils in favor of scf-context/util/FunctionClassUtils.
- Remove redundant files.
- Add FunctionInvoker deprecation annotations.
- Extend the time trigger sample with Retry policies example.

spring-cloud-function-samples/function-sample-azure-web/src/main/resources/application.properties

@@ -0,0 +1,6 @@
+spring.datasource.url=jdbc:h2:mem:testdb
+spring.datasource.driverClassName=org.h2.Driver
+spring.datasource.username=sa
+spring.datasource.password=password
+spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
+spring.jpa.defer-datasource-initialization=true

spring-cloud-function-samples/function-sample-azure-web/src/main/resources/host.json

@@ -0,0 +1,7 @@
+{
+    "version": "2.0",
+    "extensionBundle": {
+        "id": "Microsoft.Azure.Functions.ExtensionBundle",
+        "version": "[3.*, 4.0.0)"
+    }
+}