Create git patch from saqibsarwar to resolve inner block issue

[dontfeedthecode]

This PR introduces a fix provided by saqibsarwar 3 years ago or so, ticket attached to the PR. I've created a patch for this and am providing this PR as the issue has become dormant with no further input from the reporter however the solution itself is sound.

Problem

The original serialize_block() function relied on index-based matching between innerContent and innerBlocks. This approach breaks when there are nested blocks within non-string innerContent elements, leading to incorrect or incomplete serialization of deeply nested structures.

Solution

The updated serialize_block() function iterates over innerContent and dynamically processes nested innerBlocks without relying on positional indexing. For each non-string chunk in innerContent, it recursively serializes all child innerBlocks, ensuring accurate rendering and output for arbitrarily nested blocks.

Benefits

Fixes serialization issues for complex/nested block layouts
Removes dependency on matching innerContent and innerBlocks indexes
Ensures consistent and correct block output, especially for custom blocks with dynamic inner structures

Trac ticket: https://core.trac.wordpress.org/ticket/56519

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