Fix memory leak when parsing X509 certs

[alberk8]

Description

• Release/free the memory after use.

Motivation and Context

• Calling any TLS/SSL related website over multiple times will cause the call to end up with error.
• Fixes memory leak when parsing X509 certs.

How Has This Been Tested?

Run the code below:

1. 20K iteration

2. 12hours of soak time.

while (true)
{
	try
	{
	   
		Debug.WriteLine("Start HTTP Request");
		X509Certificate rootCACert1 = new X509Certificate(Resources.GetBytes(Resources.BinaryResources.rootca));
	
		
		using var httpWebRequest = (HttpWebRequest)WebRequest.Create("https://www.google.com");
		
		Debug.WriteLine("Get Request");
		httpWebRequest.Method = "GET";
		httpWebRequest.KeepAlive = true;
		
		httpWebRequest.SslProtocols = System.Net.Security.SslProtocols.Tls12;
		httpWebRequest.HttpsAuthentCert = rootCACert1;
		
		Debug.WriteLine("Get Response");
		var httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
		Debug.WriteLine("HTTP Content Length: " + httpWebResponse.ContentLength);

		byte[ ] buffer = new byte[100];
		Debug.WriteLine("Get Response Stream");
		using (Stream stream = httpWebResponse.GetResponseStream())
		{
			int bytesRead = stream.Read(buffer, 0, buffer.Length);
			string content = Encoding.UTF8.GetString(buffer, 0, bytesRead);
			Debug.WriteLine("HTTP Content: " + content);
		}

	
		Debug.WriteLine("Http(s) Closing");

		httpWebResponse.Close();
		count++;
		
		Debug.WriteLine("Count: " + count);
		Debug.WriteLine("Memory: " + nanoFramework.Runtime.Native.GC.Run(false));
	}
	catch(Exception ex)
	{
		Debug.WriteLine("HTTPS Catch Exception: " + ex.Message);
	}
	
}

1. ESP32 WROOM with and without PSRAM
2. ESP32 WROVER KIT

Screenshots

Types of changes

• Improvement (non-breaking change that improves a feature, code or algorithm)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Config and build (change in the configuration and build system, has no impact on code or features)
• Dependencies (update dependencies and changes associated, has no impact on code or features)
• Unit Tests (work on Unit Tests, has no impact on code or features)
• Documentation (changes or updates in the documentation, has no impact on code or features)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[nfbot]

@alberk8 I've fixed the checklist for you.
FYI, the correct format is [x], no spaces inside brackets.

[nfbot]

@alberk8 there are issues with the code style on the source files.
A PR was submitted with the code style fixes. Please click alberk8#1, review the changes if you want and merge it.

Make sure to follow the project code style. Check the details here on how it works and the tools required to help you with that.

[josesimoes]

Nice catch! So there was a memory leak after all... 😅