Unsupported 'cache_type' argument passed on to PyArrow's HDFS classes from WholeFileCacheFileSystem

Hi,

In fsspec 0.5.2 via Conda, it appears the fsspec.implementations.cached.WholeFileCacheFileSystem might be feeding unwanted arguments to the PyArrow lib methods, such as cache_type.
If I setup my cached Filesystem like so:

import fsspec

fs = fsspec.filesystem(
            protocol="filecache",
            target_protocol='hdfs',
            cache_storage='/mylocalfolder',
            cache_check=3600, #one hour, Number of seconds between reload of cache metadata
            check_files=True, #doesn't work with HTTP files
            expiry_time=False, #The time in seconds after which a local copy is considered useless. Set to falsy to prevent expiry. 604800 => one week
            target_options={'path': '/myhdfspath/', 'host': 'myhdfshost'}
        )

This works fine:

fs.walk('/adir')

But this does not:

of = fs.open('/adir/afile.txt')
with of as f:
    f

I get this error

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-9-f4b5281b24bb> in <module>
----> 3 of = fs.open('/adir/afile.txt')
      4 with of as f:
      5     f
      
~/conda/envs/myenv/lib/python3.7/site-packages/fsspec/implementations/cached.py in <lambda>(*args, **kw)
    259             # all the methods defined in this class. Note `open` here, since
    260             # it calls `_open`, but is actually in superclass
--> 261             return lambda *args, **kw: getattr(type(self), item)(self, *args, **kw)
    262         if item == "__class__":
    263             return type(self)

~/conda/envs/myenv/lib/python3.7/site-packages/fsspec/spec.py in open(self, path, mode, block_size, **kwargs)
    706             ac = kwargs.pop("autocommit", not self._intrans)
    707             f = self._open(
--> 708                 path, mode=mode, block_size=block_size, autocommit=ac, **kwargs
    709             )
    710             if not ac:

~/conda/envs/myenv/lib/python3.7/site-packages/fsspec/implementations/cached.py in <lambda>(*args, **kw)
    259             # all the methods defined in this class. Note `open` here, since
    260             # it calls `_open`, but is actually in superclass
--> 261             return lambda *args, **kw: getattr(type(self), item)(self, *args, **kw)
    262         if item == "__class__":
    263             return type(self)

~/conda/envs/myenv/lib/python3.7/site-packages/fsspec/implementations/cached.py in _open(self, path, mode, **kwargs)
    333 
    334         # call target filesystems open
--> 335         f = self.fs._open(path, **kwargs)
    336         with open(fn, "wb") as f2:
    337             if f.blocksize and f.size:

~/conda/envs/myenv/lib/python3.7/site-packages/fsspec/implementations/hdfs.py in <lambda>(*args, **kw)
    114             # all the methods defined in this class. Note `open` here, since
    115             # it calls `_open`, but is actually in superclass
--> 116             return lambda *args, **kw: getattr(PyArrowHDFS, item)(self, *args, **kw)
    117         if item == "__class__":
    118             return PyArrowHDFS

~/conda/envs/myenv/lib/python3.7/site-packages/fsspec/implementations/hdfs.py in _open(self, path, mode, block_size, autocommit, **kwargs)
     70         if not autocommit:
     71             raise NotImplementedError
---> 72         return HDFSFile(self, path, mode, block_size, **kwargs)
     73 
     74     def __reduce_ex__(self, protocol):

~/conda/envs/myenv/lib/python3.7/site-packages/fsspec/implementations/hdfs.py in __init__(self, fs, path, mode, block_size, **kwargs)
    169         self.mode = mode
    170         self.block_size = block_size
--> 171         self.fh = fs.pahdfs.open(path, mode, block_size, **kwargs)
    172         if self.fh.readable():
    173             self.seek_size = self.size()

~/conda/envs/myenv/lib/python3.7/site-packages/pyarrow/io-hdfs.pxi in pyarrow.lib.HadoopFileSystem.open()

TypeError: open() got an unexpected keyword argument 'cache_type'

I get a similar error for get().

Start with implementations/cached.py and implementations/hdfs.py, following the _open call shown in the traceback. Reproduce the filecache setup against HDFS and compare open() and get() argument forwarding. Done means WholeFileCacheFileSystem no longer sends unsupported cache_type arguments to PyArrow HDFS methods and both operations work.