RFR 8159935:JShell API: Reorganize execution support code into jdk.jshell.execution

[Robert Field]

In preparation for defining the execution engine library, consolidate 
jdk.internal.jshell.jdi and jdk.internal.jshell.remote as the base of 
the JDI execution control implementation library.

Only the file/class moves and corresponding renames and adjustments are 
included.  The jdk.jshell.execution package is added to module-info 
because, with this, it is exported.  These changes are broken out as a 
separate step to facilitate review.  Will be pushed with its parent issue.

Please review.

Bug:
      8159935:JShell API: Reorganize execution support code into 
jdk.jshell.execution
      https://bugs.openjdk.java.net/browse/JDK-8159935

Parent bug:
      8159118: JShell API: Provide abstract and concrete implementations 
of ExecutionControl SPI
      https://bugs.openjdk.java.net/browse/JDK-8159118

Webrev:
      http://cr.openjdk.java.net/~rfield/8159935v0.webrev/

Thanks,
Robert