[WIP] openvmm: emulated nvme configuration

[Copilot]

Working on issue #1534 to add NVMe emulated configuration options.

Implementation Complete ✅

• Analyze existing NVMe implementation and CLI structure
• Add max_ioqpairs parameter support to --nvme CLI option
• Add support for multiple NVMe controllers (automatic based on max_ioqpairs)
• Update storage builder to group namespaces by max_ioqpairs values
• Add CLI help documentation for new parameter
• Add unit tests for NvmeCli parsing
• Generate unique controller instance IDs
• Add integration tests for new functionality (optional)
• Research qcow2 support (separate task)

Features Implemented

✅ 1. max_ioqpairs configuration

• Users can specify --nvme file:disk.vhd,max_ioqpairs=128
• Defaults to 64 if not specified (backward compatible)
• Both VTL0 and VTL2 supported

✅ 2. Multiple NVMe controllers (automatic)

• Different max_ioqpairs values automatically create separate controllers
• No need for explicit controller IDs - system handles this intelligently
• Each controller gets unique instance ID and subsystem ID
• Namespaces with same max_ioqpairs are grouped together

CLI Examples

# Single controller with default max_ioqpairs=64
openvmm --nvme file:mydisk.vhd

# Single controller with custom max_ioqpairs
openvmm --nvme file:mydisk.vhd,max_ioqpairs=128

# Multiple controllers created automatically based on max_ioqpairs
openvmm --nvme file:disk1.vhd,max_ioqpairs=64 \
        --nvme file:disk2.vhd,max_ioqpairs=128 \
        --nvme file:disk3.vhd,max_ioqpairs=64 \
        --nvme file:disk4.vhd,max_ioqpairs=256

# This creates 3 controllers:
#   Controller 1: max_ioqpairs=64  (disk1.vhd, disk3.vhd)  
#   Controller 2: max_ioqpairs=128 (disk2.vhd)
#   Controller 3: max_ioqpairs=256 (disk4.vhd)

Implementation Notes

• Smart controller creation: Controllers are created automatically when different max_ioqpairs values are used
• Namespace grouping: All namespaces with the same max_ioqpairs go to the same controller
• Unique instance IDs: Each controller gets a unique GUID derived from base + max_ioqpairs
• VTL support: Works for both VTL0 and VTL2
• Backward compatibility: Existing CLI usage continues to work unchanged

This implementation satisfies both requirements from the issue:

1. ✅ max_ioqpairs=UINT32 configuration
2. ✅ Support for additional NVMe controllers

Fixes #1534.

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