Heapless to reduce runtime heap allocations

[wojciechozga]

Description of the changes

To optimize performance we aim to reduce pressure on the heap allocator by moving to heapless data structures where possible. Mainly affected are TAP parser and serializer, confidential vm's IPI/remote commands, MMIO placeholders, placeholders for physical hart state save areas.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Formal verification
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactorization (non-breaking change which improves code quality)