Automatically do a build before deploying C# function projects

[v-flyuan]

Repro steps:

1. Create a new project using C#.
2. Create a new function and add Httptrigger.
3. Select 'Function'. Then the HttpTrigger file will be opened.
4. Deploy to Azure Function App.
5. Update the code.
6. Deploy again. Verify whether you can get the updated content in Terminal window.

Expect:
The content is updated.

Actual:
The content isn't updated.

More Info:

1. This issue doesn't reproduce on JavaScript.
2. This issue also reproduce on Mac.
3. If you update the code and F5. Then deploy again, you can get the updated content.

[ejizba]

This is expected - you have to re-build your project before deploying. However, we could consider automatically doing that for the user - renamed issue to reflect that

[ejizba]

This requires waiting on the build task to complete before deploying, which isn't possible through the VS Code extension api today. However, it was just added to the proposed API here microsoft/vscode#45664

I think its worth waiting for that API rather than doing something hacky to enable this feature

cc @StephenWeatherford @nturinski