refactor(identity): rename CertificateKind to CertificateUsage

[huster-zhangpeng]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 95.45455% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
identity/src/certificate.rs	95.00%	1 Missing ⚠️

Files with missing lines	Coverage Δ
access/src/db/mod.rs	93.06% <100.00%> (ø)
identity/src/identity.rs	82.78% <100.00%> (ø)
identity/src/certificate.rs	98.46% <95.00%> (ø)

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