Add Doxygen Documentation for Public APIs

[devin-ai-integration]

Add Doxygen Documentation for Public APIs

Added comprehensive Doxygen documentation for 44 previously undocumented public APIs in wolftpm/tpm2_wrap.h, including:

• HMAC functions (HmacStart, HmacUpdate, HmacFinish)
• CSR functions (CSR_SetCustomExt, CSR_SetKeyUsage, CSR_SetSubject)
• Handle management functions (UnloadHandles, UnloadHandles_AllTransient)
• Policy functions (PolicyAuthorizeMake, PolicyPassword, PolicyAuthValue)
• Firmware upgrade functions (FirmwareUpgradeHash, FirmwareUpgrade, FirmwareUpgradeRecover, FirmwareUpgradeCancel)

Each API documentation includes:

• Brief description
• Return value descriptions
• Parameter descriptions
• Related function references

Testing: Documentation-only changes, no functional changes to test.

Link to Devin run: https://app.devin.ai/sessions/eed294a2c85949d4b8af03ef716e8920
Requested by: [email protected]

[devin-ai-integration]

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[dgarske]

Please add new line above the doxygen section for each new one added. This allows for easier readability.