Add supported platforms build setting when specifying multiple destin…

…ations

- When specifying multiple destination, the `SUPPORTED_PLATFORMS` build setting needs to be set to include the various sdks for both simulator and device

Notes:

- This was cherry-picked from a draft PR for multi-platform support #5381

Test Plan:

- Multiple destinations is not yet exposed via public as such can only be validated with unit tests at this time

Sources/TuistGenerator/Generator/ConfigGenerator.swift

@@ -256,6 +256,15 @@ final class ConfigGenerator: ConfigGenerating {
             settings["SDKROOT"] = "auto"
         }
 
+        if target.supportedPlatforms.count > 1 {
+            let simulatorSDKs = target.supportedPlatforms.compactMap(\.xcodeSimulatorSDK)
+            let platformSDKs = target.supportedPlatforms.map(\.xcodeDeviceSDK)
+            settings["SUPPORTED_PLATFORMS"] = .string(
+                [simulatorSDKs, platformSDKs].flatMap { $0 }.sorted()
+                    .joined(separator: " ")
+            )
+        }
+
         if target.product == .staticFramework {
             settings["MACH_O_TYPE"] = "staticlib"
         }

Tests/TuistGeneratorTests/Generator/ConfigGeneratorTests.swift

@@ -542,6 +542,7 @@ final class ConfigGeneratorTests: TuistUnitTestCase {
         let expectedSettings: SettingsDictionary = [
             "SDKROOT": "auto",
             "TARGETED_DEVICE_FAMILY": "1,2",
+            "SUPPORTED_PLATFORMS": "iphoneos iphonesimulator macosx",
             "LD_RUNPATH_SEARCH_PATHS[sdk=macosx*]": ["$(inherited)", "@executable_path/../Frameworks"],
             "LD_RUNPATH_SEARCH_PATHS": ["$(inherited)", "@executable_path/Frameworks"],
         ]