Move CONF_PLATFORM_VERSION to global const.py

[tomaszduda23]

What does this implement/fix?

Remove duplicated code.
Draft that I'm working on #6075 force some generic changes. I push those separetly since those can be merge independently.

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.

[probot-esphome]

Hey there @jesserockz, mind taking a look at this pull request as it has been labeled with an integration (rp2040) you are listed as a code owner for? Thanks!
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[probot-esphome]

Hey there @esphome/core, mind taking a look at this pull request as it has been labeled with an integration (esp32) you are listed as a code owner for? Thanks!
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[probot-esphome]

Hey there @esphome/core, mind taking a look at this pull request as it has been labeled with an integration (esp8266) you are listed as a code owner for? Thanks!
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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 53.45%. Comparing base (4d8b5ed) to head (0f18e68).
Report is 470 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #6629      +/-   ##
==========================================
- Coverage   53.70%   53.45%   -0.26%     
==========================================
  Files          50       50              
  Lines        9408     9544     +136     
  Branches     1654     1685      +31     
==========================================
+ Hits         5053     5102      +49     
- Misses       4056     4131      +75     
- Partials      299      311      +12     

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[kbx81]

LGTM -- thanks!