Set redis config parameters.

I have tried to add custom redis config like this:
```
### Redis instance
- name: cache
type: gcp-types/redis-v1:projects.locations.instances
properties:
parent: projects/{{ env["project"] }}/locations/us-central1
instanceId: cache
authorizedNetwork: projects/{{ env["project"] }}/global/networks/default
memorySizeGb: 1
tier: BASIC
redisConfigs:
"maxmemory-policy": "allkeys-lru" # TODO: this doesn't work for some reason
```

Doesn't seem like it's taking `redisConfigs` into account. Is it possible to set it with DM?