Modify driver invocation on swift run --repl to match new REPL behavior. (#5621)

Behaviour modified in rdar://78280429.

Resolves rdar://95793872

Author: artemcm

Sources/Build/BuildPlan.swift

@@ -2175,7 +2175,7 @@ public class BuildPlan {
     /// importing the modules in the package graph.
     public func createREPLArguments() -> [String] {
         let buildPath = buildParameters.buildPath.pathString
-        var arguments = ["-I" + buildPath, "-L" + buildPath]
+        var arguments = ["repl", "-I" + buildPath, "-L" + buildPath]
 
         // Link the special REPL product that contains all of the library targets.
         let replProductName = graph.rootPackages[0].identity.description + Product.replProductSuffix

Tests/BuildTests/BuildPlanTests.swift

@@ -1056,7 +1056,7 @@ final class BuildPlanTests: XCTestCase {
 
         let buildPath: AbsolutePath = plan.buildParameters.dataPath.appending(components: "debug")
 
-        XCTAssertEqual(plan.createREPLArguments().sorted(), ["-I\(Dep.appending(components: "Sources", "CDep", "include"))", "-I\(buildPath)", "-I\(buildPath.appending(components: "lib.build"))", "-L\(buildPath)", "-lpkg__REPL"])
+        XCTAssertEqual(plan.createREPLArguments().sorted(), ["-I\(Dep.appending(components: "Sources", "CDep", "include"))", "-I\(buildPath)", "-I\(buildPath.appending(components: "lib.build"))", "-L\(buildPath)", "-lpkg__REPL", "repl"])
 
         XCTAssertEqual(plan.graph.allProducts.map({ $0.name }).sorted(), [
             "Dep",