Support helm `set-string` parameter in `helm`

[jazzdan]

Due to the magic of YAML and dynamic typing it can be difficult to force a field to be of a certain type. For example if you use --set to set foo to "true" "true" will actually become the integer 1. This problem is described more in depth here.

To get around this Helm has a --set-string flag that forces the value that is being set to be a string. We should add support for this as a parameter to the helm builtin.

[nicks]

You can do this with helm_resource's flags param: https://github.com/tilt-dev/tilt-extensions/tree/master/helm_resource

I'm fine leaving this issue open to add set_string to the old helm() built-in, but I think most people would be happier with helm_resource

[electrofelix]

Should helm_remote be updated to use helm_resource instead of the built-in helm then? Since it too would have the same issue