[Swift] Moves grpc example to grpc/examples (#6479)

Updates generated Code

Removes grpc generation code from tests dir

Small fix to generate.sh

tests/FlatBuffers.Test.Swift/SwiftTest.sh

@@ -3,10 +3,6 @@ cd ..
 test_dir=`pwd`
 alias fbc='${test_dir}/../flatc'
 
-cd FlatBuffers.GRPC.Swift/Sources/Model
-fbc --swift --grpc greeter.fbs
-cd ${test_dir}
-
 cd ${swift_dir}/Tests/FlatBuffers.Test.SwiftTests
 fbc --swift --gen-mutable --grpc --gen-object-api -I ${test_dir}/include_test ${test_dir}/monster_test.fbs ${test_dir}/union_vector/union_vector.fbs
 fbc --swift ${test_dir}/optional_scalars.fbs