Replace Vault dependency with @KeychainStorage property wrapper

Changelog-Changed: replace Vault dependency with @KeychainStorage property wrapper
Closes: #1076

damusTests/KeychainStorageTests.swift

@@ -0,0 +1,46 @@
+//
+//  KeychainStorageTests.swift
+//  damusTests
+//
+//  Created by Bryan Montz on 5/3/23.
+//
+
+import XCTest
+@testable import damus
+import Security
+
+final class KeychainStorageTests: XCTestCase {
+    @KeychainStorage(account: "test-keyname")
+    var secret: String?
+
+    override func tearDownWithError() throws {
+        secret = nil
+    }
+
+    func testWriteToKeychain() throws {
+        // write a secret to the keychain using the property wrapper's setter
+        secret = "super-secure-key"
+        
+        // verify it exists in the keychain using the property wrapper's getter
+        XCTAssertEqual(secret, "super-secure-key")
+        
+        // verify it exists in the keychain directly
+        let query = [
+            kSecAttrService: "damus",
+            kSecAttrAccount: "test-keyname",
+            kSecClass: kSecClassGenericPassword,
+            kSecReturnData: true,
+            kSecMatchLimit: kSecMatchLimitOne
+        ] as [CFString: Any] as CFDictionary
+        
+        var result: AnyObject?
+        let status = SecItemCopyMatching(query, &result)
+        XCTAssertEqual(status, errSecSuccess)
+        
+        let data = try XCTUnwrap(result as? Data)
+        let the_secret = String(data: data, encoding: .utf8)
+        
+        XCTAssertEqual(the_secret, "super-secure-key")
+    }
+
+}