heap overflow when appending oversized manifest paths

[jmestwa-coder]

Summary

Fix a heap buffer overflow in windows_add_json_entry() when processing oversized manifest paths discovered through registry or D3DKMT enumeration.

Root Cause

• The initial allocation path always used the existing buffer size, regardless of the incoming manifest path length.
• The growth path expanded the buffer by at most a single doubling, which could still leave the destination undersized for large values.
• Appended writes were bounded by the source length instead of the remaining destination capacity.

Together, these conditions could result in writes beyond the allocated buffer when handling oversized manifest paths.

Changes

• Size the destination buffer based on the required length before writing.
• Grow the buffer until the incoming value fits.
• Return VK_ERROR_OUT_OF_HOST_MEMORY when the required size cannot be represented.
• Bound all writes using the destination buffer capacity.

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[ci-tester-lunarg]

Author jmestwa-coder not on autobuild list. Waiting for curator authorization before starting CI build.

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