build: add issue template

The Dapr CPP SDK repo should have an issues template for when end users create issues when working with the project.

Describe the solution you'd like
We should abide by a standardized issue template across all SDK repositories.

To implement, we should add a `ISSUE_TEMPLATE` directory similar to that of:
https://github.com/dapr/java-sdk/tree/master/.github/ISSUE_TEMPLATE
https://github.com/dapr/python-sdk/tree/master/.github/ISSUE_TEMPLATE

Additional context
This will help to improve contributors to easily communicate their issues, as well as maintainers to easily understand what the issue at hand is.