Adds option to auto-adjust the track height to show all features

[carolinebridge]

Adds new menu option to auto-adjust the track height to expand and shrink based on the features shown.

The functionality is as follows:

‘static’ === the track height will assume the height the user has adjusted the height to, or the configured height

‘dynamic’ === the track height will expand and shrink based on the height of the features shown

Resolves https://github.com/GMOD/jbrowse-components/issues/534

Adds a slot for this in the config:

    /**
     * #slot configuration.LinearGenomeViewPlugin.adjustTrackLayoutHeight
     */
    adjustTrackLayoutHeight: {
      type: 'string',
      defaultValue: 'static',
      model: types.enumeration('adjustTrackLayoutHeightOptions', [
        'static',
        'dynamic'
      ]),
    },