Add tooltips for JCL from jes-explorer

[1000TurquoisePogs]

Proposed changes

This PR adds hover documentation to the existing JCL language mode in the zlux-editor Monaco integration.

JCL source files already had syntax highlighting (the ISPF-style color scheme). This PR adds a hover provider so that placing the cursor over any JCL keyword or parameter name displays a brief description of what it does. No changes are made to the tokenizer or theme.

Changes:

• webClient/src/app/editor/code-editor/monaco/hiliters/jcl.ts -- added new export JCL_HOVER_DOCS: Record<string, string> containing hover documentation for 60+ JCL keywords, organized into four groups:
  • Statement types: JOB, EXEC, DD, PROC, PEND, IF/THEN/ELSE/ENDIF, INCLUDE, JCLLIB, OUTPUT, SET, CNTL/ENDCNTL, XMIT, COMMAND, EXPORT, SCHEDULE, and JES3 job-group statements (JOBGROUP, ENDGROUP, GJOB, JOBSET, SJOB, ENDSET, AFTER, BEFORE, CONCURRENT).
  • JOB statement parameters: CLASS, MSGCLASS, MSGLEVEL, NOTIFY, REGION, TIME, ADDRSPC, COND, ACCT, TYPRUN, RESTART, BYTES, LINES, PAGES, CARDS, PRTY, PERFORM.
  • EXEC statement parameters: PGM, PARM, DYNAMNBR.
  • DD statement parameters: DSN, DISP, UNIT, VOL, SYSOUT, SPACE, DCB, RECFM, LRECL, BLKSIZE, DSORG, DUMMY, DDNAME, LABEL, BUFNO, FREE, AMP, AVGREC, STORCLAS, MGMTCLAS, DATACLAS, KEYLEN, RKP, EXPDT, RETPD, SUBSYS, PATH, PATHMODE, PATHOPTS, FILEDATA.
• webClient/src/app/editor/code-editor/monaco/monaco.config.ts -- updated the JCL import to include JCL_HOVER_DOCS and registered a registerHoverProvider('jcl', ...) that resolves the word at the cursor (uppercased) against JCL_HOVER_DOCS. A secondary check extracts parameter names from PARAM= context on the line to handle sub-keywords like RECFM and LRECL.

This PR addresses Issue: zowe/zlux#538

Type of change

• New feature (non-breaking change which adds functionality)

PR Checklist

• If the changes in this PR are meant for the next release / mainline, this PR targets the "staging" branch.
• My code follows the style guidelines of this project (see: Contributing guideline)
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• New and existing unit tests pass locally with my changes
• video or image is included if visual changes are made
• Relevant update to CHANGELOG.md
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works, or describe a test method below

Testing

1. Build the editor plugin and deploy to a Zowe Desktop instance.
2. Open a JCL file (.jcl or .cntl extension) via the File Explorer. The JCL language mode and ISPF-style color theme should apply as before.
3. Hover over JCL statement keywords and verify tooltips appear:
   • Hover over JOB on the JOB card -- should show a description of the JOB statement.
   • Hover over EXEC -- should describe the EXEC statement and mention PGM= vs PROC.
   • Hover over DD -- should describe the DD statement and list key parameters.
   • Hover over PROC, PEND, IF, THEN, ELSE, ENDIF -- each should have its own tooltip.
   • Hover over INCLUDE and JCLLIB -- should describe library concatenation.
4. Hover over DD parameter keywords and verify tooltips:
   • Hover over DSN -- should describe data set naming including &&name and *.
   • Hover over DISP -- should describe status and normal/abnormal disposition values.
   • Hover over SYSOUT -- should describe JES spool output classes.
   • Hover over SPACE -- should describe TRK/CYL allocation syntax.
   • Hover over RECFM, LRECL, BLKSIZE -- each should describe the DCB sub-parameter.
5. Hover over JOB parameters:
   • Hover over CLASS, MSGCLASS, MSGLEVEL, NOTIFY, REGION, TIME, COND -- each should show a description.
6. Verify that hovering over non-keyword content (e.g. a data set name, a job name, a comment) produces no tooltip.
7. Confirm that syntax highlighting and theme are unchanged.