Add Google Cloud Tasks how-to documentation

[kazanzhy]

closes: #8208
related: #8209

Add how-to documentation for Google Cloud Tasks.
I've built successfully in a local machine and made static checks.

This PR with the #20138 also closes: #8209

[dstandish]

looks like black failed

[kazanzhy]

That's strange.
I've successfully built docs locally and I can't figure out why images build is failing

[potiuk]

That's strange. I've successfully built docs locally and I can't figure out why images build is failing

This is not images - you just should run -pre-commit and format the code with black via pre-commit.

[kazanzhy]

Now seems to be ok @dstandish
The issue was in mypy. Some methods' parameters had no types like response_view: Optional = None.
I passed response_view: Optional[Task.View] = None in according to the documentation.