[swift] Moves code to use VTablesStorage (#5888)

* Moves the code to use _vtablestorage

Rebuilt the test to confirm to the new API

Adds documentation + generates code for grpc

Reverts indentation

v0.4.0

Updated swift/readme.md

Updates VtableStorage to ensure space instead of reallocating each time

Fixes str count not being correct

* Fixes issue with boolean constant not being set + removes unused function

tests/FlatBuffers.Test.Swift/Tests/FlatBuffers.Test.SwiftTests/FlatBuffersMonsterWriterTests.swift

@@ -145,7 +145,7 @@ class FlatBuffersMonsterWriterTests: XCTestCase {
         XCTAssertEqual(vec?.x, 1)
         XCTAssertTrue(vec?.mutate(test1: 3) ?? false)
     }
-        
+    
     func readFlatbufferMonster(monster: inout MyGame.Example.Monster) {
         XCTAssertEqual(monster.hp, 80)
         XCTAssertEqual(monster.mana, 150)