[python-api] Update various params/args interfaces to use LazyDict pattern

[leonardt]

Pattern was introduced in https://github.com/rdaly525/coreir/pull/111 for instance.config

• [ ] module.modparams
• [ ] generator.modparams
• [ ] generator.genparams
• [x] instance.genargs
• [x] instance.mod
• [x] namespace.instantiables
• [x] namespace.generators
• [x] namespace.modules

[leonardt]

Moving this to pycoreir