Support Breit Wigner without energy dependent width

[shenvitor]

I am trying to use the builder to formulate BW without $ls$ coupling (no angular momentum) in this work,
for now this is not possible when doing so, because in the BW class the energy dependent width don't accept angular_momentum = None. So it might be good to add this option.

See also #139.

ampform-dpd/src/ampform_dpd/dynamics/__init__.py

Lines 18 to 44 in 92359b7

	class RelativisticBreitWigner(sp.Expr):
	s: Any
	mass0: Any
	gamma0: Any
	m1: Any
	m2: Any
	angular_momentum: Any
	meson_radius: Any
	_latex_repr_ = (
	R"\mathcal{{R}}_{{{angular_momentum}}}\left({s}, {mass0}, {gamma0}\right)"
	)
	def evaluate(self):
	from ampform.dynamics import EnergyDependentWidth # noqa: PLC0415
	s, m0, w0, m1, m2, angular_momentum, meson_radius = self.args
	width = EnergyDependentWidth(
	s=s,
	mass0=m0,
	gamma0=w0,
	m_a=m1,
	m_b=m2,
	angular_momentum=angular_momentum,
	meson_radius=meson_radius,
	name=Rf"\Gamma_{{{sp.latex(angular_momentum)}}}",
	)
	return (m0 * w0) / (m0**2 - s - width * m0 * sp.I)

[redeboer]

Longterm it's better if all these expression classes move to AmpForm. See e.g. ComPWA/ampform#423.