Task.json shouldn't need to be manually created to build .NET projects before debugging

[gregg-miskelly]

For .NET debugging, we currently need to have the user manually create a tasks.json in order to support build. We would like to find some solution to avoid the user needing to do this manually.

A few options:

1. Support simple shell commands directly inside of launch.json. So if all the user wants to do is execute a command with a default error syntax they don't need this extra file. Example:
   "preLaunchCommand": "dotnet compile"
   Which would execute 'dotnet compile' in the workspace directory.
   -or-
2. Support auto-generating a tasks.json when creating launch.json. This way we can give them a good default value of it and the user doesn't need to manually enter it.
   -or-
3. Support defining tasks in an extension's package.json. So the user only needs to create a launch.json if they want to do something weird.

[isidorn]

FYI @weinand @dbaeumer

[isidorn]

@gregg-miskelly after discussing with @dbaeumer we think it is best that we help the user generate tasks.json file. We can not move the task running logic inside the launch.json since then we would have to replicate all the tasks logic into debug.

Is the task that you want to run a preLaunchTask, or would the user want to run it independent of debug?

[gregg-miskelly]

Ideally, it would be nice if people could run it some other way too. But running it as a preLaunchTask is the biggest thing that we care about.

[isidorn]

After discussing with @dbaeumer we should introduce a way for an extension to contribute an 'initial' tasks.json. This should all live in the task framework, however this is not a small effort so moving it to the backlog and assigning to Dirk.