Support `VirtualEnv`, `RequirementsFile`, `PythonRuntime`, `Package`, and `PyPIRepo`

[andyk]

This issue depends on #278.

Now that #278 and #336 are done, we should be able to add new Component types that allow our DAG to accurately capture more of the types of dependencies involved in running a Python program, including the following:

• VirtualEnv
• PythonRuntime
• RequirementsFile
• Package
• PypiRepo

And here is a registry-like nested list that gives you a sense of how these all might relate to each other (note that the nested list formatting gets maxed out so some of the inner-most indents aren't tabbed over far enough):

• Command:
  • runtime:
    • PythonRuntime
      • version: str # e.g., 3.9.4
  • function_name: str
  • object_manager: # this attribute currently named 'component'
    • ObjectManager (ObjectManager is an abstract class w/ subtypes: Module, Class, Instance)
  • env:
    • VirtualEnv
      • pip_packages:
        • list:
          • PipPackage
            • package_dependencies:
              • list:
                • PipPackage
                • PipPackage
            • module_dependencies:
              • list:
                • Module
                • Module
            • requirements_files:
              • list:
                • RequirementsFile
                  • path: str
                  • repo:
                  • Repo (one of PyPIRepo, GitHubRepo, LocalRepo)
                  • PyPIRepo
                  • project_name: agentos
                  • default_version: 0.1.0
                • RequirementsFile