Adds Validation to NewsBlur and Feedbin Views

Disables add account button when username or password are empty.

iOS/Account/FeedbinAddAccountView.swift

@@ -99,6 +99,7 @@ struct FeedbinAddAccountView: View {
 					Spacer()
 				}
 			}
+			.disabled(!validateCredentials())
 		}
 	}
 	
@@ -110,6 +111,13 @@ struct FeedbinAddAccountView: View {
 		return Text("").multilineTextAlignment(.center)
 	}
 	
+	private func validateCredentials() -> Bool {
+		if (accountEmail.trimmingWhitespace.count == 0) || (accountPassword.trimmingWhitespace.count == 0) {
+			return false
+		}
+		return true
+	}
+	
 	private func retrieveCredentials() {
 		if let account = account {
 			do {

iOS/Account/NewsBlurAddAccountView.swift

@@ -116,6 +116,7 @@ struct NewsBlurAddAccountView: View, Logging {
 					Spacer()
 				}
 			}
+			.disabled(!validateCredentials())
 		}
 	}
 	
@@ -127,6 +128,13 @@ struct NewsBlurAddAccountView: View, Logging {
 		return Text("").multilineTextAlignment(.center)
 	}
 	
+	private func validateCredentials() -> Bool {
+		if (accountUserName.trimmingWhitespace.count == 0) || (accountPassword.trimmingWhitespace.count == 0) {
+			return false
+		}
+		return true
+	}
+	
 	private func executeAccountCredentials() async throws {
 		let trimmedUsername = accountUserName.trimmingWhitespace