Support transforms in connection details

I would like greater control in how connection details are written to kubernetes secrets. One way to achieve this could be by allowing patch & transform style transforms in the `connectionDetails` items, like so:

```yaml
kind: Composition
spec:
writeConnectionSecretsToNamespace: other-namespace
mode: Pipeline
pipeline:
- step: patch-and-transform
functionRef:
name: function-patch-and-transform
input:
apiVersion: pt.fn.crossplane.io/v1beta1
kind: Resources
resources:
- name: key
base:
# Removed for brevity
spec:
forProvider:
# Removed for brevity
writeConnectionSecretToRef:
namespace: docs
name: key1
connectionDetails:
- name: my-username
type: FromConnectionSecretKey
transforms:
- type: string
string:
type: Format
format: 'username = "%s"'
fromConnectionSecretKey: username
```

This would allow me to use the resulting connection secret in the `varFiles` property of Terraform provider Workspaces.