Support ${taskVar:name} variables from problem matcher named capture groups

[hediet]

Fixes #303361

What

Introduces ${taskVar:name} variables that extract named capture groups from a task problem matcher's endsPattern and make them available for variable substitution in launch configurations and other resolved contexts.

How

1. WatchingProblemCollector.tryFinish() — When the endsPattern matches, matches.groups is extracted into a Map<string, string> and attached to the BackgroundProcessingEnds event.

2. IProblemCollectorEvent — Extended with an optional capturedVariables field.

3. TerminalTaskSystem — Listens for capturedVariables in the state change event and registers them via IConfigurationResolverService.contributeVariable() using the taskVar: prefix.

4. VariableKind.TaskVar — Added to the enum for completeness.

Example

// tasks.json — endsPattern with named capture group
"endsPattern": "  current session url: (?<componentExplorerUrl>.*)"

// launch.json — reference the captured value
"url": "${taskVar:componentExplorerUrl}"

Files changed

File	Change
src/vs/workbench/contrib/tasks/common/problemCollectors.ts	Extract named groups, extend event
src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts	Register captured variables
src/vs/workbench/services/configurationResolver/common/configurationResolver.ts	Add TaskVar to VariableKind
src/vs/workbench/services/configurationResolver/test/.../configurationResolverService.test.ts	Test for taskVar resolution
.vscode/launch.json	Use ${taskVar:componentExplorerUrl} for Component Explorer
.vscode/tasks.json	Updated endsPattern with named capture group

[Copilot]

Pull request overview

Adds support for ${taskVar:name} variables that surface named capture groups from a background task problem matcher’s endsPattern, enabling downstream variable substitution (e.g. in launch configurations) based on values emitted in task output.

Changes:

• Extend problem collector end events to optionally carry named regex capture groups (matches.groups) as a capturedVariables map.
• Register captured variables in TerminalTaskSystem as contributed configuration resolver variables under the taskVar: prefix.
• Add VariableKind.TaskVar and a configuration resolver test validating ${taskVar:...} substitution, plus update workspace .vscode task/launch configs to use the new variable.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/vs/workbench/contrib/tasks/common/problemCollectors.ts	Extracts named capture groups from endsPattern matches and propagates them via the problem collector state change event.
src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts	Consumes capturedVariables and contributes taskVar:<name> variables to the configuration resolver.
src/vs/workbench/services/configurationResolver/common/configurationResolver.ts	Adds TaskVar to VariableKind for taskVar recognition.
src/vs/workbench/services/configurationResolver/test/electron-browser/configurationResolverService.test.ts	Adds test coverage for resolving a contributed taskVar:<name> variable in a configuration object.
.vscode/tasks.json	Updates the Component Explorer task endsPattern to include a named capture group for the URL.
.vscode/launch.json	Switches Component Explorer launch URLs to ${taskVar:componentExplorerUrl}.