add a `validate=False` option for `graph_objects` and `px` figures

There's already an issue outlining the effects graph_object validation has on plot generation time. Users can bypass this performance hit by replacing the graph_objects with dict and then display the plot with plotly.offline.iplot(fig, validate=False) or if they are creating graphs in Dash, they can forgo the plotly.py library altogether and just use a dict in their Graph component's figure argument.

This solution can greatly improve the performance of Dash apps but it means that Dash users with expensive graphs have to choose between using px/plotly.py's update methods and optimally fast code.

I wonder if a way to turn off validation, especially in Dash apps, would help Dash users get the best of both worlds.

cc @matthewchan15

审查 issue #1052 以及 graph_objects 和 px 现有的图形生成路径，然后跟踪 validation 在 offline.iplot 和相关图形消费者之前是如何应用的。定义 validate=False 选项应如何在这些 API 中工作，包括 Dash 用例，并验证禁用 validation 能改善目标路径，同时不改变正常的已验证行为。