[External] Replace embedded tablesaw.plotly by Maven dependencies (#265)

[HannesWell]

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Description

This PR (part of #265) replaces the source code of source code of the tablesaw-jsplot sub-project embedded in matheclipse-external with a corresponding Maven dependency.

The Maven coordinates used are:

	<dependency>
		<groupId>tech.tablesaw</groupId>
		<artifactId>tablesaw-jsplot</artifactId>
		<version>0.42.0</version>
	</dependency>

The tablesaw sources embedded in matheclipse-io are not affected.

@axkr is there a reason to not use a Maven dependency?
In contrast to the sources of tablesaw in matheclipse-io those embedded in matheclipse-external seem not to have matheclipse references?

[gitpod-io]

[HannesWell]

I just noticed that tablesaw-jsplot has a transitive dependency to tablesaw-core which is partially embedded into matheclipse-io. I assume only the part not depending on tablesaw-core was embedded into matheclipse-core.
So I suggest to request changes to the tablesaw project so tablesaw can be made a complete Maven-dependency for core and io and issue #265 can be resolved entirely.