Integrate MIRA support of branching ratios in equation-to-model feature

[liunelson]

Description

• Update latex-to-sympy instructions to remove .expand() (prevents loss of (1 - p) factors)
• Update LaTeX style guide to retain all factors of the form (1 - p) but expand all others such as b * S(t) * (I(t) + A(t) + H(t))
• Update style guide to handle named functions like sin, cos, exp, log
• Add guardrails to the latex-to-sympy instructions

Resolves #6601