Consider to change RelativePattern ctor argument order

[jrieken]

re #34831

Maybe it's me but it feels weird to have a relative pattern that puts the pattern before the base. While the reading goes "pattern 'relative to' base", the mental model goes like "base + pattern"

new vscode.RelativePattern('*.ts', folder);

vs

// closer to how I would manually write a pattern
new vscode.RelativePattern(folder, '*.ts');