RemoteBuilder: Does not support INSTANCE_ARGS that have a space

## Affected builder image
`gcr.io/cloud-builders-community/remote-builder`

## Expected Behavior
It can accept an INSTANCE_ARGUMENT with a space such as "--min-cpu-platform=Intel Haswell"
## Actual Behavior
The Space in the argument causes the create command to break.

## Steps to Reproduce the Problem

1.Supply a --min-cpu-platform=Intel Haswell to the remote builder as an INSTANCE_ARGUMENT.
2.Supply a --min-cpu-platform='Intel Haswell' to the remote builder as an INSTANCE_ARGUMENT.
3.Supply a --min-cpu-platform="Intel Haswell" to the remote builder as an INSTANCE_ARGUMENT.

Each fails with something like:
```
- Invalid value for field 'resource.minCpuPlatform': '"Intel'. Invalid CPU platform.
- Invalid value for field 'resource.name': 'Haswell"'. Must be a match of regex '(?:[a-z](?:[-a-z0-9]{0,61}[a-z0-9])?)'
```

## Additional Info