Restore debugger functionality when using static linking

In order to enable debugging of static modules it's required to register their corresponding .swiftmodule using -add_ast_path flag in each runnable target. Visit WWDC22's Debug Swift debugging with LLDB for more information.

Use this option to pass -add_ast_paths to the linker and enable LLDB commands such as p and po. Without it, LLDB may fail to reconstruct Swift types when you use static linking and can report errors like the following:

error: type for self cannot be reconstructed: type for typename "<typename>" was not found (cached).
error: Couldn't realize Swift AST type of self. Hint: using `v` to directly inspect variables and fields may still work.

Pass the required LinkerAstPaths enum value to Config.GenerationOptions

Geko/Config.swift

import ProjectDescription

let config = Config(
    ...
    generationOptions: Config.GenerationOptions.options(
        addAstPathsToLinker: Config.GenerationOptions.LinkerAstPaths.forAllDependencies
    ),
)

Available LinkerAstPaths values:

• disabled
• forAllDirectDependencies
• forAllDependencies
• forFocusedTargetsOnly

disabled does not add any paths to linker

forAllDirectDependencies adds the paths of all direct dependencies to each runnable target or tests bundle.

forAllDependencies adds the paths of all direct and transitive dependencies to each runnable target or test bundle. This is recommended in most cases; however, in large projects it can result in an "Argument list too long" error. If that happens, use forFocusedTargetsOnly.

forFocusedTargetsOnly works in the same way as forAllDirectDependencies but keeps only what is in focus.