[config] Retain path information in validated configuration

[clydebarrow]

What does this implement/fix?

Currently read_config() in esphome/config.py strips the path information from its validated config before returning.

By retaining that information, components can retrieve the source file and line associated with Ids during code generation, allowing line number directives to be inserted - e.g.:

      #line 462 "lvgl-package.yaml"
      lv_button = lv_btn_create(main_page->page);

This is already done in ESPHome for lambdas, which capture the path information which can be very helpful in identifying C++ code errors.

This is used by the LVGL PR, broken out here to keep core changes from the component PR.

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.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 53.88%. Comparing base (4d8b5ed) to head (8ae3d98).
Report is 688 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #6785      +/-   ##
==========================================
+ Coverage   53.70%   53.88%   +0.17%     
==========================================
  Files          50       50              
  Lines        9408     9619     +211     
  Branches     1654     1698      +44     
==========================================
+ Hits         5053     5183     +130     
- Misses       4056     4112      +56     
- Partials      299      324      +25     

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