Allow arbitrary `Mapping` types when setting properties, rather than only `dict`

Currently, it seems that only dict is allowed when setting properties. It would be better if an arbitrary Mapping type were allowed, since that grants the user the flexibility to control properties with alternative data structures such as a ChainMap.

As far as I can tell, this could be done just by changing the validate_coerce() logic to check isinstance(v, Mapping) instead of isinstance(v, dict), e.g. on this line.

Example

This raises a ValueError:

from collections import ChainMap

import plotly.graph_objects as go


layout = ChainMap(
    dict(width=1000),
    dict(width=500, height=500),
)
go.Figure(layout=layout)

Start in packages/python/plotly/_plotly_utils/basevalidators.py at the validate_coerce() logic referenced in the issue. Check how the Figure(layout=ChainMap(...)) example is validated, then verify that arbitrary Mapping inputs are accepted without changing existing dict behavior.