feat: add integration tests with TPM enabled

[HJK-X]

Runs integration tests inside a VM with TPM+FDE enabled.

See this action:
https://github.com/HJK-X/snap-http/actions/runs/21369743041/job/61510905420

[Copilot]

Pull request overview

This PR adds integration tests that run inside a VM with TPM (Trusted Platform Module) and FDE (Full Disk Encryption) enabled, validating the snap-http functionality in a secure boot environment.

Changes:

• Created new integration test suite for TPM-enabled environment testing recovery key management operations
• Added GitHub Actions workflow to automate VM-based integration testing with TPM emulation
• Included shell script to mount the host directory and execute tests inside the VM

Reviewed changes

Copilot reviewed 3 out of 8 changed files in this pull request and generated 3 comments.

File	Description
tests/integration_tpm/test_api.py	Implements integration tests for keyslot management and recovery key operations in TPM environment
tests/integration_tpm/assets/run_tests.sh	Provides script to mount host directory and run integration tests inside the VM
.github/workflows/integration-tpm.yml	Configures GitHub Actions workflow to spin up QEMU VM with TPM emulation and execute integration tests

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