Remove side effect of import watertap

[bknueven]

Importing watertap executes the following lines of code:

watertap/watertap/core/plugins/solvers.py

Lines 207 to 215 in abf7614

	## reconfigure IDAES to use the ipopt-watertap solver
	import idaes
	_default_solver_config_value = idaes.cfg.get("default_solver")
	_idaes_default_solver = _default_solver_config_value._default
	_default_solver_config_value.set_default_value("ipopt-watertap")
	if not _default_solver_config_value._userSet:
	_default_solver_config_value.reset()

which changes the behavior of the get_solver method in IDAES.

We should remove this side effect for downstream projects so they can explicitly specify the solver. One idea is to implement our own get_solver method so it is explicit which default set of options you are getting.