Made swiftlint plugin env-var enabled optional

CONTRIBUTING.md

@@ -80,6 +80,13 @@ To test from the command line you need `swift` version `5.0+`.
 swift test
 ```
 
+### SwiftLint
+the SwiftLint Xcode plugin can be optionally enabled during development by using an environmental variable when opening the project from the commandline. 
+```
+OTEL_ENABLE_SWIFTLINT=1 open Package.swift
+```
+Note: Xcode must be completely closed before running the above command, close Xcode using `⌘Q` or running `killall xcode` in the commandline.  
+
 ### Make your modifications
 
 Always work in a branch from your fork:

Package.resolved

@@ -126,15 +126,6 @@
         "version" : "1.4.0"
       }
     },
-    {
-      "identity" : "swiftlintplugins",
-      "kind" : "remoteSourceControl",
-      "location" : "https://github.com/SimplyDanny/SwiftLintPlugins",
-      "state" : {
-        "revision" : "f9731bef175c3eea3a0ca960f1be78fcc2bc7853",
-        "version" : "0.57.1"
-      }
-    },
     {
       "identity" : "thrift-swift",
       "kind" : "remoteSourceControl",

Package@swift-5.9.swift

@@ -2,6 +2,7 @@
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import PackageDescription
+import Foundation
 
 let package = Package(
     name: "opentelemetry-swift",
@@ -33,7 +34,7 @@ let package = Package(
         .package(url: "https://github.com/apple/swift-protobuf.git", from: "1.20.2"),
         .package(url: "https://github.com/apple/swift-log.git", from: "1.4.4"),
         .package(url: "https://github.com/apple/swift-metrics.git", from: "2.1.1"),
-        .package(url: "https://github.com/SimplyDanny/SwiftLintPlugins", from: "0.57.1")
+//        .package(url: "https://github.com/SimplyDanny/SwiftLintPlugins", from: "0.57.1")
     ],
     targets: [
         .target(name: "OpenTelemetryApi",
@@ -291,8 +292,14 @@ extension Package {
     }
 }
 
-for target in package.targets {
-  target.plugins = [
-    .plugin(name: "SwiftLintBuildToolPlugin", package: "SwiftLintPlugins"),
-  ]
+if ProcessInfo.processInfo.environment["OTEL_ENABLE_SWIFTLINT"] != nil {
+  package.dependencies.append(contentsOf: [
+    .package(url: "https://github.com/SimplyDanny/SwiftLintPlugins", from: "0.57.1")
+  ])
+
+  for target in package.targets {
+    target.plugins = [
+      .plugin(name: "SwiftLintBuildToolPlugin", package: "SwiftLintPlugins"),
+    ]
+  }
 }