id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
766826777,MDU6SXNzdWU3NjY4MjY3Nzc=,4691,Non-HTTPS remote URLs no longer work as input for open_zarr,20627856,closed,0,,,5,2020-12-14T19:00:19Z,2021-02-28T04:48:52Z,2021-02-28T04:48:52Z,NONE,,,,"<!-- Please include a self-contained copy-pastable example that generates the issue if possible.

Please be concise with code posted. See guidelines below on how to provide a good bug report:

- Craft Minimal Bug Reports: http://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports
- Minimal Complete Verifiable Examples: https://stackoverflow.com/help/mcve

Bug reports that follow these guidelines are easier to diagnose, and so are often handled much more quickly.
-->

**What happened**:

On 0.16.2 and later, passing a non-HTTPS remote URL path (e.g. `gs://...`) as input to [`open_zarr()`](https://github.com/pydata/xarray/blob/96e1aea0271aeeeda7c8f33a8491d5e2a06f9ddc/xarray/backends/zarr.py#L507) results in a `KeyError` or `GroupNotFoundError`:

```python
>>> import xarray as xr
>>> xr.open_zarr(""gs://cmip6/AerChemMIP/AS-RCEC/TaiESM1/histSST/r1i1p1f1/AERmon/od550aer/gn/"", consolidated=True)
KeyError: '.zmetadata'
>>> xr.open_zarr(""gs://cmip6/AerChemMIP/AS-RCEC/TaiESM1/histSST/r1i1p1f1/AERmon/od550aer/gn/"", consolidated=False)
GroupNotFoundError: group not found at path ''
```

**What you expected to happen**:

With versions 0.16.1 and earlier, passing a non-HTTPS remote URL path to `open_zarr()` as input would successfully open the remote store, provided that a package to handle the specific filesystem was available in the environment and the proper storage options were supplied.

**Minimal Complete Verifiable Example**:

Same as above, but with `decode_times=False` to circumvent a cftime dependency:

```python
import xarray as xr

xr.open_zarr(
    ""gs://cmip6/AerChemMIP/AS-RCEC/TaiESM1/histSST/r1i1p1f1/AERmon/od550aer/gn/"",
    consolidated=True,
    decode_times=False,
)
```

**Anything else we need to know?**:

From a brief debug of the code, it looks like this error is a result of `open_zarr()` now calling [`open_dataset(engine=""zarr"")`](https://github.com/pydata/xarray/blob/96e1aea0271aeeeda7c8f33a8491d5e2a06f9ddc/xarray/backends/api.py#L315) to open the Zarr store.

In this function, the remote URL path is now passed through [`_normalize_path()`](https://github.com/pydata/xarray/blob/96e1aea0271aeeeda7c8f33a8491d5e2a06f9ddc/xarray/backends/api.py#L178) where it is not recognized as a remote URL (this check is done by [`is_remote_uri()`](https://github.com/pydata/xarray/blob/96e1aea0271aeeeda7c8f33a8491d5e2a06f9ddc/xarray/core/utils.py#L602) which only checks for HTTPS) and is instead interpreted as a relative path in the local filesystem, where it does not exist.

I'm not sure if this meant to be expected behavior, as the documentation on [reading datasets in the cloud](https://xarray.pydata.org/en/stable/io.html#cloud-storage-buckets) does not show an example using a URL path as input, and only suggests to use a `MutableMapping`. However, this is a use case that worked before 0.16.2, and now no longer works.

I think this could be resolved by expanding `is_remote_uri()` to check for other common remote URIs (e.g. `gs:`, `s3:`, etc.).

**Environment**:

<details><summary>Output of <tt>xr.show_versions()</tt></summary>

<!-- Paste the output here xr.show_versions() here -->
```
INSTALLED VERSIONS
------------------
commit: None
python: 3.9.1 | packaged by conda-forge | (default, Dec  9 2020, 01:07:06) [MSC v.1916 64 bit (AMD64)]
python-bits: 64
OS: Windows
OS-release: 10
machine: AMD64
processor: Intel64 Family 6 Model 142 Stepping 10, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None
LOCALE: English_United States.1252
libhdf5: None
libnetcdf: None

xarray: 0.16.2
pandas: 1.1.5
numpy: 1.19.4
scipy: None
netCDF4: None
pydap: None
h5netcdf: None
h5py: None
Nio: None
zarr: 2.6.1
cftime: 1.3.0
nc_time_axis: None
PseudoNetCDF: None
rasterio: None
cfgrib: None
iris: None
bottleneck: None
dask: None
distributed: None
matplotlib: None
cartopy: None
seaborn: None
numbagg: None
pint: None
setuptools: 51.0.0.post20201207
pip: 20.3.1
conda: None
pytest: None
IPython: 7.19.0
sphinx: None
```
</details>
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