[gradle] Create an empty resource dir with "podspec" task instead "podInstall"

[terrakok]

By mistake the generation resources directory was linked to "podInstall" task instead "podspec".

Fixes https://github.com/JetBrains/compose-multiplatform/issues/4720

Testing

• create a new Compose App project with an iOS integration via Cocoapods
• add some multiplatform resources
• clean all caches and build dirs
• call "pod install"
• check that first run of the iOS app works fine

Release Notes

Fixes - Resources

• Create an empty resource dir with "podspec" task instead "podInstall"