Add new component mcp3426 7 8

[mdop]

What does this implement/fix?

Adds support for the 4 channel 16 bit ADC chips of the MCP3426/7/8 family. Structure is based on the ADS1115, but the measurement is done asynchronously.

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#3810

Test Environment

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

Example entry for config.yaml:

mcp3428:
  address: 0b1101000

sensor:
  - platform: mcp3428
    name: "Channel 1"
    multiplexer: 1
    resolution: 12
    gain: 8
    id: mcp3428_sensor1

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.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 54.05%. Comparing base (4d8b5ed) to head (160ba51).
Report is 507 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #6675      +/-   ##
==========================================
+ Coverage   53.70%   54.05%   +0.34%     
==========================================
  Files          50       50              
  Lines        9408     9554     +146     
  Branches     1654     1687      +33     
==========================================
+ Hits         5053     5164     +111     
- Misses       4056     4066      +10     
- Partials      299      324      +25     

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