Fix WSL path URI decoding under Windows

[jfcherng]

Python 3.3>>> from LSP.plugin.core.url import filename_to_uri, parse_uri, urlparse

Python 3.3>>> filename_to_uri('\\\\wsl$\\Ubuntu-20.04\\home\\jfcherng\\Desktop\\docs\\a.py')
'file://wsl%24/Ubuntu-20.04/home/jfcherng/Desktop/docs/a.py'
           
Python 3.3>>> parse_uri('file://wsl%24/Ubuntu-20.04/home/jfcherng/Desktop/docs/a.py')
('file', '\\\\wsl%24\\Ubuntu-20.04\\home\\jfcherng\\Desktop\\docs\\a.py')
                 ^^^ this is wrong. should be $

Python 3.3>>> urlparse('file://wsl%24/Ubuntu-20.04/home/jfcherng/Desktop/docs/a.py')
ParseResult(scheme='file', netloc='wsl%24', path='/Ubuntu-20.04/home/jfcherng/Desktop/docs/a.py', params='', query='', fragment='')
                                      ^^^ this is wrong. should be $

Notice that netloc is wsl%24 after urlparse(). We need to decoding that before doing "\\\\{}\\{}".format(netloc, path) just like what we do for path.

Related issue: https://discord.com/channels/280102180189634562/280157083356233728/963549081886666784

[rwols]

Can you add a test for this so we don’t regress in the future? There are windows-specific tests that run in the CI