Wizard pauses

[dwhswenson]

This PR will address the need for pauses in the wizard. Currently, the wizard hops from one step to the next very quickly; a brief pause (and possibly some visual cues) will improve UX by making it easier to track what is happening.

This addresses one of the targets for before v0.3 raised in #57:

• Add pauses at various points to give better UX
  • creating subvolumes
  • after naming an object

Tasks

• Write basic pausing module, which can be reused (and which allows customization of delays)
• Tests for pausing module
• Add pause before creating subvolumes
• Add pause after each object is created
• Fix unit tests so that 'nopause' pause style is used in test suite

[codecov]

Codecov Report

Merging #62 (61b8da4) into main (34cf3a0) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main       #62   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           51        52    +1     
  Lines         2143      2181   +38     
=========================================
+ Hits          2143      2181   +38     

Impacted Files	Coverage Δ
paths_cli/wizard/pause.py	100.00% <100.00%> (ø)
paths_cli/wizard/two_state_tps.py	100.00% <100.00%> (ø)
paths_cli/wizard/volumes.py	100.00% <100.00%> (ø)
paths_cli/wizard/wizard.py	100.00% <100.00%> (ø)

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[dwhswenson]

This is ready for review and comment. I will leave it open for at least 24 hours, merging no earlier than Tue 02 Nov 18:00 GMT (14:00 my local).

I think this is an improvement over the previous UX, but I'm very much open to other UX improvements along these lines.

[sroet]

1 question about the use of global, otherwise LGTM