Define APIs for loading rules

Define fine-grained APIs for loading rules to be used by the rule
evaluation engine. The loader supports loading rules based on some app
install metadata keys such as PackageName, AppCertificate, InstallerName, and
InstallerCertificate.

Bug: 141970289
Test: N/A
Change-Id: Iec171974f9e9a63049cac10464a97116eea20b2b