Migrate many SciJava Common subsystems #295

It runs through the same Runner, meets the same preprocessors, harvests
its inputs through the same dialog in whichever toolkit, and can sit in a
menu beside a Java command. Nothing above this layer knows which it is --
a claim now tested rather than asserted: ScriptWidgetsTest renders a
Groovy script's parameters with the Swing widgets and drives its
callbacks through an actual JSpinner.

javax.script is the first backend, not the only one. ScriptLanguage and
ScriptSession are the SPI; JsrLanguage turns every JSR-223 engine on the
classpath into one, so Groovy, Jython, JRuby, Clojure and BeanShell cost
nothing and declare nothing. GraalVM polyglot and Appose become further
ScriptLanguages without this layer changing.

Callbacks work for scripts, which SciJava Common never managed. It
resolved `callback = "foo"` by reflecting a Java method, leaving a script
nothing to name; here the name is resolved by whatever kind of code the
executable is, and for a script that means a function it defined. Three
things make it work:

- a *session* rather than a one-shot eval, so the functions still exist
  when a parameter changes;
- what the function changed is converted back into the parameters --
  Groovy's `celsius * 9 / 5 + 32` is a BigDecimal, and convert3 knows
  what the parameter's declared type wants;
- every declared parameter is bound, including unfilled ones, since a
  language that resolves names at run time fails on an unbound name
  rather than seeing null.

Validators and choicesFrom come along for the same ride.

The #@ header syntax is unchanged, because tens of thousands of scripts
are written in it. Declaration lines are blanked rather than removed, so
the language's own error messages keep pointing at the line the author is
looking at -- #@ being a comment in Python and a syntax error in Groovy,
leaving it in was not an option.

Not ported: the ScriptProcessor chain, which existed to rewrite a script
before evaluation and was used for parameters and a shebang, both of
which the header reader does directly. ScriptService has no equivalent.
ScriptREPL, ScriptInterpreter, AutoCompleter and CodeGenerator belong
with the script editor.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_013gJpzGd3ksbME4CN6Tu2ni