Add FMI 3.0 support and refactor API to camelCase with CLI subcommands

[prudhomm]

• Add FMI 3.0 generation support for both Dymola (2024+) and OpenModelica (1.21+) backends
• Refactor public API to use camelCase naming convention (compileFmu, checkCompilers, getCompiler)
• Restructure CLI with click.group() subcommands: mo2fmu compile and mo2fmu check
• Maintain backward compatibility with deprecated legacy functions that emit warnings
• Update test framework to support FMI3 as well as both co-simulation and model-exchange