GDEY042T81 e-paper displays support

[mgruener]

Add support for GDEY042T81 style 4.2" B/W e-paper displays to the waveshare display component.

The display used to develop and test the code was a display from WeAct studio: https://github.com/WeActStudio/WeActStudio.EpaperModule

I found some hints online that this might also be the display used in the Waveshare 4.2" B/W Rev 2.2, but right now I have no way to verify this. The "4.20in" and "4.20in-bV2" model drivers in the waveshare component did not work with the display I have (hence the PR).

• 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)
• Code quality improvements to existing code or addition of tests
• Other

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

• GDEY042T81 e-paper displays support esphome-docs#4574

Test Environment

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

Example entry for config.yaml:

display:
  - platform: waveshare_epaper
    cs_pin: GPIO6
    dc_pin: GPIO7
    busy_pin: GPIO4
    reset_pin: GPIO3
    model: gdey042t81
    rotation: 0
    full_update_every: 5
    update_interval: 10s
    reset_duration: 200ms

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.

[probot-esphome]

Hey there @clydebarrow, mind taking a look at this pull request as it has been labeled with an integration (waveshare_epaper) you are listed as a code owner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 53.81%. Comparing base (4d8b5ed) to head (3ed0408).
Report is 2008 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #8061      +/-   ##
==========================================
+ Coverage   53.70%   53.81%   +0.10%     
==========================================
  Files          50       50              
  Lines        9408     9856     +448     
  Branches     1654     1360     -294     
==========================================
+ Hits         5053     5304     +251     
- Misses       4056     4230     +174     
- Partials      299      322      +23     

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