fix: use namespace for separator

[gaige]

Use the IMAP namespace separator based on the information retrieved from the IMAP command to retrieve namespaces, falling back to '/' if the command isn't available or the results don't include the private namespace.

Resolves #551

[codecov]

Codecov Report

Attention: Patch coverage is 14.28571% with 12 lines in your changes missing coverage. Please review.

Project coverage is 61.39%. Comparing base (d6128ea) to head (23996fc).
Report is 40 commits behind head on master.

Files with missing lines	Patch %	Lines
parsedmarc/mail/imap.py	14.28%	6 Missing ⚠️
parsedmarc/__init__.py	0.00%	5 Missing ⚠️
parsedmarc/mail/mailbox_connection.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #552      +/-   ##
==========================================
+ Coverage   59.88%   61.39%   +1.50%     
==========================================
  Files          12       12              
  Lines        1578     1650      +72     
==========================================
+ Hits          945     1013      +68     
- Misses        633      637       +4     

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[seanthegeek]

A couple of things:

• I don't see get_folder_separator() defined anywhere when a do a quick search of the repo. Where is it defined at?
• Let's set the folder separator once instead of calling get_folder_separator() for each path.

[gaige]

@seanthegeek Yeah, somehow I missed the other files, they're in the mail classes, they should be there now. I've updated to get the separator once.

[gaige]

I have verified that this works in my configuration with Dovecot. The IMAPClient namespace method is used for determining the separator uses the IMAP standard call for determining the separator, so I don't expect any problems with other servers, however I've put in fallbacks for both IMAP and the base class to use the / separator which was used originally. In the case of the IMAP class, / will be returned if the call doesn't contain the expected parameters.