[Solvers] Thermo-mechanical coupling

[yujidu]

Describe the PR
Thermo-mechanical MPM solvers

** Explicit TM solver**

• Modify the solver flow based on the code style
• Create a new 'mpm_scheme' class for explicit TM solver
• Add particle temperature constraint/heat source constraint
• Add a function to calculate the critical time step size
• Generalize the virtual heat flux method

** Implicit TM solver**

• Create a new 'mpm_scheme' class for the implicit TM solver
• Improve the convergence criteria
• Linearization of the heat flux term and the plastic heat term