Mixed path styles when operating cross-platform (windows)

[ronpandolfi]

Expected Behavior

Event model should resolve joining paths of different styles when it joining the root to the resource.

Current Behavior

Currently, mixed styles result, where, for example, a windows root append to a posix resource results in a path with both / and \\.

Possible Solution

Inspiration from ophyd (bluesky/ophyd#703) seems relevant; likely some usage of PathLib to compose paths better.

Steps to Reproduce (for bugs)

1. Have data collected from EPICS AD on linux
2. Access data from databroker on windows
3. Check path composition by breaking at

   event-model/event_model/__init__.py

   Line 417 in a1ea6af

   resource_path = os.path.join(root, resource_path)

Context

This issue may affect operation of databroker on windows, depending on if the handler accepts mixed path styles.

Your Environment

Windows; databroker prerelease 1.0.0b2

(discussed in coalition call on 11/8)