Exporting big 3d meshes resulted in huge files since the data is stored as plain text in the html file. By storing the data in compressed base64 the file size can be reduced by 85%.

Reduction Examples:
96.8mb to 15.4mb
42.2mb to 2.7mb
27.6mb to 6.8mb

Code PR

• I have read through the contributing notes and understand the structure of the package. In particular, if my PR modifies code of plotly.graph_objects, my modifications concern the codegen files and not generated files.
• I have added tests (if submitting a new feature or correcting a bug) or
  modified existing tests.
• For a new feature, I have added documentation examples in an existing or
  new tutorial notebook (please see the doc checklist as well).
• I have added a CHANGELOG entry if fixing/changing/adding anything substantial.
• For a new feature or a change in behaviour, I have updated the relevant docstrings in the code to describe the feature or behaviour (please see the doc checklist as well).