Introduce SwiftBundler library target (#66)

* Create SwiftBundler library target; Keep Main.swift in executable target swift-bundler

* Make essentials public

* Make appImagePIDs public for Linux

* Give format script executable permission

* Format

* Fix access level for PSProcess typealias on Linux

* Move process termination to dedicated function

* Update generate_docs.sh to match what happens on CI

* Typealias must be public for Linux

* Fix default init

* Use official Swift argument parser

* Fix Signal.rawValue access level on Windows

* Rename Main.swift to swift-bundler.swift to satisfy Windows compiler

* Fix swift-bundler description

* Refine swift-bundler main

* Refactor main

Author: ctreffs

Package.resolved

@@ -7,12 +7,13 @@ let package = Package(
   platforms: [.macOS(.v10_15)],
   products: [
     .executable(name: "swift-bundler", targets: ["swift-bundler"]),
+    .library(name: "SwiftBundler", targets: ["SwiftBundler"]),
     .library(name: "SwiftBundlerRuntime", targets: ["SwiftBundlerRuntime"]),
     .library(name: "SwiftBundlerBuilders", targets: ["SwiftBundlerBuilders"]),
     .plugin(name: "SwiftBundlerCommandPlugin", targets: ["SwiftBundlerCommandPlugin"]),
   ],
   dependencies: [
-    .package(url: "https://github.com/stackotter/swift-arg-parser", revision: "b1b5373"),
+    .package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.5.0"),
     .package(url: "https://github.com/apple/swift-log", from: "1.5.4"),
     .package(url: "https://github.com/pointfreeco/swift-parsing", .upToNextMinor(from: "0.13.0")),
     .package(url: "https://github.com/stackotter/TOMLKit", from: "0.6.1"),
@@ -39,8 +40,9 @@ let package = Package(
     .package(url: "https://github.com/apple/swift-async-algorithms", from: "1.0.3"),
   ],
   targets: [
-    .executableTarget(
-      name: "swift-bundler",
+    .executableTarget(name: "swift-bundler", dependencies: ["SwiftBundler"]),
+    .target(
+      name: "SwiftBundler",
       dependencies: [
         "TOMLKit",
         "Rainbow",
@@ -51,7 +53,7 @@ let package = Package(
         .product(name: "Crypto", package: "swift-crypto"),
         .product(name: "SwiftASN1", package: "swift-asn1"),
         .product(name: "X509", package: "swift-certificates"),
-        .product(name: "StackOtterArgParser", package: "swift-arg-parser"),
+        .product(name: "ArgumentParser", package: "swift-argument-parser"),
         .product(name: "Logging", package: "swift-log"),
         .product(name: "Parsing", package: "swift-parsing"),
         .product(name: "SwiftSyntax", package: "swift-syntax"),
@@ -169,7 +171,7 @@ let package = Package(
 
     // The target containing documentation
     .target(
-      name: "SwiftBundler",
+      name: "SwiftBundlerDocumentation",
       path: "Documentation",
       exclude: ["preview_docs.sh"]
     ),