[NV-GO-1] API 🚀: Validate MX Record Setup for Inbound Parse Functionality

[NonsoAmadi10]

What does this PR do?

• Adds Inbound Parser functionality for validating mx records
• Closes #8

How should this be tested manually?

• Run the following:

package main

import ( "context" "fmt" novu "github.com/novuhq/go-novu/lib" "log" )

func main() { apiKey := "" ctx := context.Background()

    novuClient := novu.NewAPIClient(apiKey, &novu.Config{})
    resp, err := novuClient.InboundParserApiGet(ctx)
    if err != nil {
    log.Fatal("novu error", err.Error())
    return
}

fmt.Println(resp.Data.MxRecordConfigured)

}

Any Background Context?
- N/A

[NonsoAmadi10]

@unicodeveloper @prajjwaldimri I have made changes to the application and even fix the test issue. I look forward to your feedback again