Update azure key vault connector

[aneeshafedo]

Description

• Change default http version of the connector from HTTP/2 to HTTP/1.1
• Update the openAPI contract related to the getSecrets API to accept null responses from the server
• Update the client related documentation in Module.md

Fixes https://github.com/ballerina-platform/ballerina-extended-library/issues/552

One line release note:

• Release azure.keyvault connector version 1.6.1

Type of change

Please delete options that are not relevant.

• 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 not work as expected)
• This change requires a documentation update

How Has This Been Tested?

test program sample:

import ballerina/io;
import ballerinax/azure.keyvault;

public function main() returns error? {
    keyvault:ConnectionConfig clientConfig = {
        auth : {
            token: "<access-token>"

        }
    };
    keyvault:Client baseClient = check new (clientConfig, serviceUrl = "https://<your-key-vault-name>.vault.azure.net/");
    keyvault:SecretListResult secrets = check baseClient->getSecrets("7.0");
    io:print(secrets);
}

Test Configuration:

• Ballerina Version: 2201.4.1 / 2201.7.1
• Operating System: Ubuntu
• Java SDK: Java 17

Checklist:

Changes to OpenAPI definition

• Modified info section of the OpenAPI definition file - Example

  • description - what the connector is about
  • x-ballerina-init-description OpenAPI extension - connector initialization details
  • x-ballerina-display OpenAPI extension - connector name and path to the connector icon

• Added proper description each API Key, if API Key authentication is defined in OpenAPI definition file

Changes to connector module

• Added license header at the top of each .bal file.
• Added Package.md as per the guide here
• Added Module.md for the module of the connector as per the guide here
• Added connector icon to the root of the connector. Icon needs to be a png of 200x200 px size with name icon.png
• Added Ballerina.toml file with following information. For keywords refer to guide

Verifying connector module

• Compiled the connector successfully with the targeted ballerina version.
• Conducted smoke tests on the connector (Recommended when OpenAPI definition is obtain from an unofficial source)

Security checks

• Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines?
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets?