Add URL validation for organization, repository, and enterprise arguments

[brianaj]

External PR from @AakashSuresh2003 (#1464) to add validation that detects when users accidentally provide URLs instead of names for org/repo/enterprise arguments.

This addresses issue #1180 by providing clear, user-friendly error messages when URL patterns are detected.

Changes:

• Added IsUrl() extension method using .NET's Uri.TryCreate() for robust URL detection
• Added validation to all command args classes that accept org/repo/enterprise names
• Validation checks for http/https URLs and provides clear error messages
• Comprehensive test coverage across gei, ado2gh, and shared commands

Key features: ✅ Uses standard .NET Uri.TryCreate() validation (not custom pattern matching) ✅ Only detects proper http/https URLs (no false positives) ✅ Clear error messages explaining expected format ✅ 47 new test cases covering all affected commands

Fixes #1180

All 1019 tests passing ✅

[github-actions[bot]]

Unit Test Results

    1 files      1 suites   10m 25s ⏱️ 1 018 tests 1 018 ✅ 0 💤 0 ❌ 1 019 runs  1 019 ✅ 0 💤 0 ❌

Results for commit 94d4c0a8.

:recycle: This comment has been updated with latest results.

[github-actions[bot]]

Package	Line Rate	Branch Rate	Complexity	Health
ado2gh	72%	71%	726	➖
Octoshift	83%	73%	1766	✔
bbs2gh	83%	78%	663	✔
gei	81%	73%	608	✔
Summary	81% (7856 / 9735)	74% (1908 / 2593)	3763	✔