Revert updates to Microsoft.Azure.Functions.* packages for plugins (m…

…icrosoft#590)

### Motivation and Context

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Azure functions tend to break silently when the
`Microsoft.Azure.Functions.*` packages are not of the correct versions.
With the current versions, the web-searcher plugin cannot find the
functions using the function core tool, i.e. `func start`.

### Description
Downgrade the `Microsoft.Azure.Functions.*` versions to previous ones
that have been tested extensively.

<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->

### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [ ] The code builds clean without any errors or warnings
- [ ] The PR follows the [Contribution
Guidelines](https://github.com/microsoft/chat-copilot/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/chat-copilot/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [ ] All unit tests pass, and I have added new tests where possible
- [ ] I didn't break anyone 😄

plugins/web-searcher/WebSearcher.csproj

@@ -8,10 +8,11 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http" Version="3.1.0" />
+    <!-- Make sure the app is thoroughly tested after any Microsoft.Azure.Functions.* package updates. -->
+    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http" Version="3.0.13" />
     <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.OpenApi" Version="1.5.1" />
-    <PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk" Version="1.16.0" />
-    <PackageReference Include="Microsoft.Azure.Functions.Worker" Version="1.19.0" />
+    <PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk" Version="1.13.0" />
+    <PackageReference Include="Microsoft.Azure.Functions.Worker" Version="1.18.0" />
   </ItemGroup>
 
   <ItemGroup>

plugins/web-searcher/local.settings.json

@@ -1,7 +1,7 @@
 {
     "IsEncrypted": false,
     "Values": {
-        "AzureWebJobsStorage": "",
+        "AzureWebJobsStorage": "UseDevelopmentStorage=none",
         "FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated"
     },
     "Host": {