[vs-code-extension] extracting pattern with variables

[Demivan]

Extending on #103

Smart extraction of string interpolation:

Allow selecting `Hello, ${userName}` for extraction.
When extracting it should generate Hello, {$userName} in the ftl file. And in code it should pass userName as a parameter.

[samuelstroschein]

The implementation seems complicated.

1. The arguments need to be detected.
   While trivial in the example above e.g. ${} for JavaScript, inlang strives to be compatible with any (most) software environments. The latter entails that the string interpolation needs to be detected for X different programming languages.
2. The replacementPatternOptions property from the config needs to be expanded to pass arguments.

The first things that comes to my mind is a new property in the config stringInterpolationSyntax, or deriving string interpolation syntaxes from the file ending.

• .ts -> ${variable}
• .dart -> `'$variable'
• etc.