fix(passkey-crypto): use base64url everywhere for the PRF salt #2516

Job	Run time
Generate head API spec	8m 22s
Generate merge base API spec	7m 53s
Check specs identical	3s
Check breaking changes	-1s
Generate vacuum reports for API spec	-1s
Linter Override	-1s
API Spec Check	3s
	16m 18s

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