rewrite w/ multiple dispatch

[atharvas]

Reimplementing key components of LaSR using multiple dispatch. The code compiles, but test coverage right now is basically 0.

[online test cases] (To be executed on github actions)

• Add test cases to test LaSR integration (ie: use LaSROptions to execute SymbolicRegression.jl test cases).
• Coverage for concept summarization.
• Coverage for LLM crossover operator.
• Coverage for all LLM mutation operators.
• Coverage for concept evolution.
• Expression printing and parsing homomorphism.
• Test case for ensuring prompts are well-structured.
• Prompt parsing test cases.

[offline test cases] (To be executed locally)

• Test cases for LLM handshake
• Test case for LaSR MLJ tutorial.

[atharvas]

MilesCranmer#398 (comment) should address this. Test cases are passing locally now.