Consolidate typing for `coords`

[williambdean]

coords have a mix of types in the codebase. Some places:

pymc/pymc/model/core.py

Line 458 in 4ad7fa8

coords=None,

The conversion type:

pymc/pymc/model/core.py

Lines 911 to 914 in 4ad7fa8

	@property
	def coords(self) -> dict[str, tuple | None]:
	"""Coordinate values for model dimensions."""
	return self._coords

pymc/pymc/model/core.py

Line 1065 in 4ad7fa8

values: Sequence | np.ndarray,

pymc/pymc/backends/arviz.py

Line 126 in 4ad7fa8

def coords_and_dims_for_inferencedata(model: Model) -> tuple[dict[str, Any], dict[str, Any]]:

Seems to be a mix of Sequence and Sequence | np.ndarray so some
consolidation would be nice. For example, there is already a various amount of
typing for other objects like dims and shape:

pymc/pymc/distributions/shape_utils.py

Lines 88 to 98 in 4ad7fa8

	# User-provided can be lazily specified as scalars
	Shape: TypeAlias = int | TensorVariable | Sequence[int | Variable]
	Dims: TypeAlias = str | Sequence[str | None]
	DimsWithEllipsis: TypeAlias = str | EllipsisType | Sequence[str | None | EllipsisType]
	Size: TypeAlias = int | TensorVariable | Sequence[int | Variable]
	# After conversion to vectors
	StrongShape: TypeAlias = TensorVariable | tuple[int | Variable, ...]
	StrongDims: TypeAlias = Sequence[str]
	StrongDimsWithEllipsis: TypeAlias = Sequence[str | EllipsisType]
	StrongSize: TypeAlias = TensorVariable | tuple[int | Variable, ...]

My main concern is not within pymc package directly but in the downstream
usage where using dict[str, Any] is probably the most common way to type
coords. So exposing would have some typing benefit.