feat: implement FIPS 140-2/140-3 compliance

[alexsander-souza]

Make MAAS operable on FIPS-enabled Ubuntu 24.04 LTS hosts by detecting
FIPS mode at runtime and enforcing FIPS-approved algorithms across all
components.

Key changes:

• FIPS mode detection utilities
• FIPS API exposure: fips_active field on GET /v3/, fips_supported annotations on power-types
• FIPS API boundary enforcement: SSH key and TLS certificate import validation (422 rejection)
• SSH algorithm hardening: FIPS allow-lists applied to hmc, mscm, wedge power drivers via connect_ssh()
• IPMI cipher suite 17 enforcement in FIPS mode
• Fernet→AES-256-GCM migration for region↔rack RPC encryption with backward-compatible Fernet decryption
• OMAPI HMAC-MD5→HMAC-SHA256 upgrade (unconditional)
• X.509 serial number CSPRNG (secrets.randbits), RSA≥2048/ECDSA P-256 key constraints
• PostgreSQL BMC index MD5→SHA256 replacement (Alembic migration 0022)
• SHA-1 display uses flagged with usedforsecurity=False
• TLS 1.2 minimum version at key construction sites (vmware, simplestreams, certificates)
• VMware driver SSL context remediation (ssl.PROTOCOL_SSLv23→create_default_context)
• AMT driver HTTPS enforcement and TLS verification in FIPS mode
• Unsupported power driver rejection (apc, eaton, raritan, dli, msftocs, recs, seamicro, ucsm, moonshot)
• Go FIPS activation via GODEBUG=fips140=on wrapper scripts (snap + debian)
• Structured security log event constants (FIPS_mode_detected, FIPS_crypto_error, etc.)
• Power driver FIPS classification registry (DriverFIPSStatus enum)

[maas-lander]

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