Fix constructor highlighting when opening parenthesis on new line

[Copilot]

Syntax highlighting breaks for all code following a constructor when the opening parenthesis is placed on a new line:

public class TestClass
{
    public TestClass
    (
        string s
    )
    {
    }

    public void Method()  // All highlighting lost from here onwards
    {
    }
}

Root cause: The constructor-declaration pattern used a lookahead (?=identifier\s*\() that only matched when both the constructor name and ( were on the same line. When split across lines, property-declaration matched instead, consuming the identifier and breaking subsequent parsing.

Changes:

• Reordered class-or-struct-members patterns to check constructor-declaration before property-declaration and field-declaration
• Changed constructor pattern from (?=@?[_[:alpha:]][_[:alnum:]]*\s*\() to (@?[_[:alpha:]][_[:alnum:]]*)\s*(?=\(|$) to match identifiers at end-of-line
• Moved identifier capture from internal match to beginCaptures for cleaner pattern structure

The pattern now matches when the identifier is followed by ( on the same line OR at end-of-line, with the actual ( matched by the subsequent parenthesized-parameter-list include.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Syntax highlighting breaks with newline in constructor</issue_title>
<issue_description>Issue originally posted at dotnet/vscode-csharp#4190

Issue Description

Syntax highlighting fails for methods after constructor if the parenthesis are moved to a new line.

Steps to Reproduce

1. Write a constructor with at least one parameter.
2. Now format it so the opening parenthesis is in the next line.
3. Now add a method after the constructor.

Expected Behavior

The lines after the constructor should have correct syntax highlighting.

Actual Behavior

All text is white.

Logs

OmniSharp log

Details

Post the output from Output-->OmniSharp log here

C# log

Details

Post the output from Output-->C# here

Environment information

VSCode version: 1.50.1
C# Extension: 1.23.5

Dotnet Information

.NET Core SDK (reflecting any global.json): Version: 3.1.301 Commit: 7feb845744

Runtime Environment:
OS Name: Windows
OS Version: 10.0.18362
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\3.1.301\

Host (useful for support):
Version: 3.1.5
Commit: 65cd789777

.NET Core SDKs installed:
2.1.201 [C:\Program Files\dotnet\sdk]
2.1.202 [C:\Program Files\dotnet\sdk]
2.1.502 [C:\Program Files\dotnet\sdk]
2.1.503 [C:\Program Files\dotnet\sdk]
2.1.505 [C:\Program Files\dotnet\sdk]
3.1.301 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.19 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.19 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.0.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.19 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.1.5 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET Core runtimes or SDKs:
https://aka.ms/dotnet-download

Visual Studio Code Extensions

Extension	Author	Version
atlascode	atlassian	2.8.3
cpptools	ms-vscode	1.1.0
csharp	ms-dotnettools	1.23.5
debugger-for-chrome	msjsdiag	4.12.11
docomment	k--kato	0.1.18
git-easy	bibhasdn	1.11.0
git-graph	mhutchie	1.27.0
gitlens	eamodio	10.2.3
hexeditor	ms-vscode	1.3.0
remote-wsl	ms-vscode-remote	0.50.1
vscode-drawio	hediet	1.0.3
vscode-eslint	dbaeumer	2.1.13
vscode-language-pack-es	MS-CEINTL	1.50.2
vscode-markdownlint	DavidAnson	0.37.2
vscode-yaml	redhat	0.12.0

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

• Fixes Syntax highlighting breaks with newline in constructor #326

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