Preview `maxZoom` setting only respected after chart update

[wpickett-trimble]

The mermaid.vscode.maxZoom configuration setting is only respected after an update has been made to a chart being previewed. Regardless of the user configuration for this setting, the initial preview of a Mermaid chart is limited to 500% zoom (i.e. maxZoom = 5).

Expected behavior

When opening a Mermaid Chart preview, the user's maxZoom configuration setting is respected.

Actual behavior

The chart is limited to a maximum 500% zoom level until an update to the underlying chart code is made.

Reproduction steps

• Set the mermaid.vscode.maxZoom setting to 10 in the user's settings.json for VS Code

• Create a test.mmd file in the workspace, with the following content:

  flowchart LR
  
  foo --> bar
  

• Open the Mermaid preview by right-clicking within a test.mmd editor and selecting MermaidChart: Preview Diagram, or selecting MermaidChart: Preview Diagram from the VS Code command palette.

• In the newly-opened preview panel that opens, zoom in as far as possible. Note that it is limited to 500% zoom.

• While the preview panel is still open, update test.mmd with the following content:

  flowchart LR
  
  foo --> bar
  bar --> baz
  

• In the preview panel, attempt to zoom in further. Note that you can now zoom to 1000% (corresponding to maxZoom = 10).