Add list targets command and clarify target terminology

[brondani]

Fixes

• Enhance cmsis.json settings management, schema and docs vscode-cmsis-solution#511 (comment)

Changes

• Add list targets as the preferred command for listing <target-type>[@<target-set>] selections.
• Retain list target-sets as a backward-compatible alias.
• Update CLI help, API comments, and schema descriptions to distinguish targets from target sets.
• Extend unit tests to cover the new command and legacy alias.

The terminology now reflects that selections may identify either a target type alone or a target type with a target set. Existing scripts using list target-sets remain supported.

Checklist

• 🤖 This change is covered by unit tests (if applicable).
• 🤹 Manual testing has been performed (if necessary).
• 🛡️ Security impacts have been considered (if relevant).
• 📖 Documentation updates are complete (if required).
• 🧠 Third-party dependencies and TPIP updated (if required).

Note: the global / copyright (pull_request) failure is unrelated to the changes in this PR. It was introduced earlier by a defect in PR #2587 and has already been reported in issue #2599.

[github-actions]

Test Results

  2 files   -    41   14 suites   - 113   9m 40s ⏱️ - 9m 31s
482 tests  -   662  482 ✅  -   645  0 💤  - 17  0 ❌ ±0 
964 runs   - 1 463  964 ✅  - 1 405  0 💤  - 58  0 ❌ ±0 

Results for commit 923c54b. ± Comparison against base commit 66cb607.

This pull request removes 662 tests.

AuxCmdTests ‑ MkdirCmdTest
AuxCmdTests ‑ RmdirCmdTest
AuxCmdTests ‑ TouchCmdTest
BuildSystemGeneratorTests ‑ GenAuditFile
BuildSystemGeneratorTests ‑ GenAuditFile_WithOut_Existing_Audit_File
BuildSystemGeneratorTests ‑ GenAuditFile_With_Existing_Audit_File
BuildSystemGeneratorTests ‑ GetString
BuildSystemGeneratorTests ‑ StrConv
BuildSystemGeneratorTests ‑ StrNorm
CBuildGCCTests ‑ Asm
…

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.59%. Comparing base (66cb607) to head (923c54b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2598   +/-   ##
=======================================
  Coverage   72.58%   72.59%           
=======================================
  Files         185      185           
  Lines       30602    30603    +1     
  Branches    18009    18009           
=======================================
+ Hits        22213    22215    +2     
  Misses       6080     6080           
+ Partials     2309     2308    -1     

Flag	Coverage Δ
projmgr-cov	87.97% <100.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
tools/projmgr/include/ProjMgr.h	100.00% <ø> (ø)
tools/projmgr/src/ProjMgr.cpp	86.57% <100.00%> (+0.01%)	⬆️

... and 1 file with indirect coverage changes

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[jkrech]

LGTM