Add state listeners to rotary_encoder

[clydebarrow]

What does this implement/fix?

Currently the rotary_encoder component maintains listeners for clockwise and anti-clockwise rotation events; this PR adds
listeners for computed state position changes.

This is intended for use by other components.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other

Related issue or feature (if applicable): fixes

Pull request in esphome-docs with documentation (if applicable): esphome/esphome-docs#

Test Environment

• ESP32
• ESP32 IDF
• ESP8266
• RP2040
• BK72xx
• RTL87xx

Example entry for config.yaml:

# Example config.yaml

Checklist:

• The code change is tested and works locally.
• Tests have been added to verify that the new code works (under tests/ folder).

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in esphome-docs.

[jesserockz]

It is a sensor, you can just use add_on_state_callback or add_on_raw_state_callback...

[clydebarrow]

True, but that uses float so restricts the monotonic values reported to roughly +/- 2^23 after which it will start reporting changes at half the actual rate. While that's a corner case, reporting as int does not have that problem.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (25ab6f0) 53.70% compared to head (93404f4) 53.64%.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #6035      +/-   ##
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- Coverage   53.70%   53.64%   -0.07%     
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  Files          50       50              
  Lines        9403     9386      -17     
  Branches     1653     1404     -249     
==========================================
- Hits         5050     5035      -15     
  Misses       4055     4055              
+ Partials      298      296       -2     

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