Add analyzer for Enum.GetValues() with code fix to use generated method

[Copilot]

Adds analyzer NEEG008 to detect Enum.GetValues() calls on enums with [EnumExtensions] and suggest the generated GetValues() method for better performance.

Implementation

• GetValuesAnalyzer: Detects both Enum.GetValues(typeof(TEnum)) and Enum.GetValues<TEnum>() patterns, reporting as Information-level diagnostic
• GetValuesCodeFixProvider: Replaces with non-extension static method ExtensionsClass.GetValues(), auto-adding namespace imports when needed
• Tests: 15 test cases covering generic/non-generic variants, external enums, edge cases

Example

Before:

[EnumExtensions]
public enum Status { Active, Inactive }

var values = Enum.GetValues(typeof(Status));        // NEEG008
var values2 = Enum.GetValues<Status>();             // NEEG008

After applying fix:

var values = StatusExtensions.GetValues();
var values2 = StatusExtensions.GetValues();

Follows patterns from existing analyzers (ParseAnalyzer, ToStringAnalyzer, etc.).

Original prompt

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This section details on the original issue you should resolve

<issue_title>Create analyzer to detect usages of Enum.GetValues() and suggest replacing with the generated GetValues() method</issue_title>
<issue_description>- Only enums which are decorated with [EnumExtensions] should be considered

• The analyzer should be written using the same style as existing analyzers.
• A code fixer should be provided, and should similarly have tests
• The suggestion/fix should use the non-extension method GetValues implementation
• All Enum.GetValues() overloads should be suggested for replacement.
• Follow the patterns used by the ParseAnalyzer, ParseCodeFixProvider and ParseAnalyzerTests
• The analyzer should be written as Information level</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Create analyzer to detect usages of Enum.GetValues() and suggest replacing with the generated GetValues() method #192

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[github-actions]

Test Results

    180 files  ±  0      180 suites  ±0   3h 22m 54s ⏱️ + 49m 14s
 21 801 tests + 15   21 797 ✅ + 15   4 💤 ±0  0 ❌ ±0 
388 446 runs  +342  388 374 ✅ +342  72 💤 ±0  0 ❌ ±0 

Results for commit 4ca03ff. ± Comparison against base commit b3d1817.

♻️ This comment has been updated with latest results.

[andrewlock]

Updated to NEEG0009