RFR 8170162: jshell tool: no mechanism to programmatically launch

[Robert Field]

Goldilocks and the three launching mechanisms...

She lay down in the first bed, but it was too hard.
     java.util.spi.ToolProvider (8169821) has a severe impedance 
mismatch: the use of Writers, no InputStream, and no flexibility.

Then she lay in the second bed, but it was too soft.
     javax.tools.ToolProvider (8170044) would require significant 
changes that are not possible at this time, it is limited, and is old 
mechanism.

Then she lay down in the third bed and it was just right. Goldilocks 
fell asleep.
     jdk.jshell.tool (8170162) provides a matching, clean, and 
configurable launching mechanism

Please review...

Bug:

     8170162: jshell tool: no mechanism to programmatically launch
     https://bugs.openjdk.java.net/browse/JDK-8170162

Sub-Tasks (tiny tweaks to other repos):

     8170194: jshell tool (jdk repo): launch tool from JShellToolProvider
     https://bugs.openjdk.java.net/browse/JDK-8170194

     8170195: jshell tool (make): update javadoc generation for jdk.jshell
     https://bugs.openjdk.java.net/browse/JDK-8170195

Webrevs:

     http://cr.openjdk.java.net/~rfield/8170162v0.webrev/

     http://cr.openjdk.java.net/~rfield/8170194v0.webrev/

     http://cr.openjdk.java.net/~rfield/8170195v0.webrev/

API:

     http://cr.openjdk.java.net/~rfield/8170162v0.jshellAPI/

SpecDiff:

http://cr.openjdk.java.net/~rfield/8170162v0.specdiff/overview-summary.html

Thanks,
Robert