Add an evaluation code lens

Similar to the [Haskell language server](https://github.com/haskell/haskell-language-server/#features), add an evaluation code lens. This could use the configured Curry executable (`curry.languageServer.curryPath`, which is `pakcs` by default) and then invoke it e.g. like this:

`pakcs :load [current module] :eval [expression] :quit`

No file or test is named in the issue. Start by locating the language-server code that provides code lenses and reads curry.languageServer.curryPath, then trace how the configured Curry executable can receive the shown :load, :eval, and :quit commands. Done means an evaluation lens is available for a current module and expression and uses the configured executable.

Written by the indexing model from the issue text.