GitHub release files like https://github.com/fluxcd/helm-controller/releases/download/v0.14.0/helm-controller.crds.yaml
seems to be hosted on Azure and it seems that there are egress limits that can be reached, e.g.:
```xml
<?xml version="1.0" encoding="utf-8"?><Error><Code>ServerBusy</Code><Message>Egress is over the account limit.
RequestId:f4a46b38-001e-0046-2437-ec16e2000000
Time:2021-12-08T13:28:03.8542138Z</Message></Error>
```
This patch allows to have a clear Error message instead of just `missing Resource metadata`:
```
Error: accumulating resources: accumulation err='accumulating resources from 'https://github.com/fluxcd/source-controller/releases/download/v0.19.0/source-controller.crds.yaml': URL returned error 503 (Service Unavailable)': evalsymlink failure on '/private/var/folders/hq/ttl6jyh539q55fz6282w0jyc0000gn/T/kustomize-3508224975/releases/download/v0.19.0/source-controller.crds.yaml' : lstat /private/var/folders/hq/ttl6jyh539q55fz6282w0jyc0000gn/T/kustomize-3508224975/releases: no such file or directory
```
Signed-off-by: Sylvain Rabot <sylvain@abstraction.fr>
* Move api/filesys to kyaml/filesys
* Add deprecated version of api/filesys with aliases to new code
* Use new kyaml/filesys package and update dependencies
* Migrate to kyaml/filesys and update dependencies
* Skip tests that break on Windows
