Improve generated server properties documentation

[ctubbsii]

• Use gson to pretty-print default values for JSON property types
• Use html tables instead of markdown to support multi-line
  descriptions and default values
• Support markdown syntax in property descriptions by enabling kramdown
  support for mixing markdown and html table cells
• Stop replacing newlines with <br> in property descriptions, and just
  accept the property description written in markdown
• Fix documentation for restarting the manager when a
  compaction.coordinator property changes
• Improve PropertyTest and PropertyTypeTest to ensure property
  descriptions and default values restrictions are strictly enforced
• Update Property descriptions to use markdown, and for improved
  readability
• Add more links to other properties and classes in the Property
  descriptions
• Wrap some Property descriptions better, and remove trailing
  backslashes, since they are no longer needed for markdown paragraphs
• Where examples are used for setting properties, show in a style that
  can be used directly in the properties config file, with proper
  escaping
• Standardize using 0 when a zero-value has special meaning for a
  property, so that the value described is shown the same way a user
  would set it (i.e. say 0 instead of "zero", to make it clear that
  the configuration would look like a literal 0)
• Use class.getName() where possible for class references, and fix
  several classes whose class name was incorrectly hard-coded
• Fix several properties to use PropertyType.CLASSNAME instead of
  PropertyType.STRING when their values are a class name type
• Fix generated document to use the short name of the property type,
  rather than the enum name, which is only in code
• Remove old information about CDATA, since configuration is no longer
  XML-based
• Remove reference to deprecated properties, and update docs to specify
  replacements
• Update PropertyType descriptions to use markdown also

This fixes #5902 and #5903

[DomGarguilo]

Took a look through the rendered page differences and everything looks good. For context/reference here is what I saw:

Current view:

New view:

Things are a bit more spread out but the table is definitely formatted better.

Current view:

New view:

This shows the improved code formatting and line wrapping.

[keith-turner]

@ctubbsii was there anything you wanted to do before merging this? I have not looked at the changes, was just looking through PRs and saw it was approved.

[ctubbsii]

@ctubbsii was there anything you wanted to do before merging this?

I have a local branch I need to reconcile and see if this includes everything. Will try to do that tomorrow, but prioritizing looking at the accumulo-classloader PR first