Extract Constant Refactoring: Add way to extract all instances of selected expression

From https://github.com/microsoft/vscode/issues/85507

Search Terms

• refactor
• extract
• extract constant / extract function

Suggestion

For the code:

function doStuff() {
    console.log('hello')
    console.log('hi')
    console.log('hello')
}

If I run extract constant on the string 'hello'`, it'd be nice if we offered a way to extract all instances of that expression in the current scope. This would turn the code into:

function doStuff() {
    const text = 'hello'
    console.log(text)
    console.log('hi')
    console.log(text)
}

Use Cases

• Help reducing duplicated code
• Speed up code cleanup

Start by reviewing the originating VS Code issue #85507 and the TypeScript refactoring implementation; the payload does not name a source file or test entry point. Define the behavior for extracting every matching expression in the current scope, then verify that the example produces one constant and replaces both matching occurrences.