Update backward incompatible changes topics

[dshevtsov]

Purpose of this PR (required)

• Fixes BIC documentation for Magento Commerce doesn't have the same info as Magento Open Source #1445 - Merges topics for open-source and commerce into one topic.
• Removes topics for B2B only backward incompatible changes because we do not have the appropriate automation.
• Delivers Generated backward incompatible changes for 2.3 #4216

Affected URLs (required)

• https://devdocs.magento.com/guides/v2.3/release-notes/backward-incompatible-changes/index.html

• https://devdocs.magento.com/guides/v2.3/release-notes/backward-incompatible-changes/reference.html

• https://devdocs.magento.com/guides/v2.2/release-notes/backward-incompatible-changes/index.html

• https://devdocs.magento.com/guides/v2.2/release-notes/backward-incompatible-changes/reference.html

• https://devdocs.magento.com/guides/v2.1/release-notes/backward-incompatible-changes/index.html

• https://devdocs.magento.com/guides/v2.1/release-notes/backward-incompatible-changes/reference.html

• https://devdocs.magento.com/guides/v2.0/release-notes/backward-incompatible-changes/index.html

• https://devdocs.magento.com/guides/v2.0/release-notes/backward-incompatible-changes/reference.html

Additional information

Internal ticket: MAGEDOC-2632
Merging instructions: must be merged together with the backporting PR #4227

whatsnew
Updated backward incompatible changes topics:

• Merged topics for open-source and commerce backward incompatible changes into single topic.
• Added a section for changes introduced to the 2.3-develop branch codebase after 2.3.1 release.

[magento-cicd2]

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✅ dshevtsov
❌ magento-team

[dshevtsov]

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