Feature: improvements to working patterns and flexibility index

[martinctc]

Summary

This branch addresses some feature and documentation requests for both workpatterns_classify() and flex_index().

Changes

The changes made in this PR are:

1. Reintroduce old visual of heatmap distribution of activity across hours of the day (Feature request: reintroduce and improve 'old' workpatterns_classify() visual #143).
2. Replaced colours of heatmap distribution visual from red to #1d627e (Feature request: reintroduce and improve 'old' workpatterns_classify() visual #143)
3. Update wording to reflect the recurring nature of breaks (Documentation: refer to 'breaks' as 'recurring disconnection time' for working patterns #158)
4. Added ability to run percentages for identify_shifts_wp() (Feature request: show % for identify_shifts_wp() #155)

Examples

Checks

• All R CMD checks pass
• roxygen2::roxygenise() has been run prior to merging to ensure that .Rd and NAMESPACE files are up to date.
• NEWS.md has been updated.

Notes

This fixes #143, #155, #158.