feature request: CPU/Mem Profile subclasses with scenario-specific member predicates

[Lslightly]

Now profile.qll only support Profile class. We need more specific subclasses like CPU/Mem Profiles.

[Lslightly]

comparing scenario:

1. same repository(same database), different configurations. 1 database with many profiles.
2. different build method(different database), same configurations. many databases with 1 profile each.

[Lslightly]

CPU Profile:

• support calculate flat/cum time of certain function
• support calculate percent of certain function
• support generate cum time for certain lines