feat: Add Go Modules and add Go 1.19 compatibility

[AlaricWhitney]

Fixes

Adds Go Modules, and also adding a v2 directory as per current golang standards as per https://go.dev/blog/v2-go-modules.

This PR also makes minor adjustments to correct compatibility with Go 1.19.

Checklist

• [x] I acknowledge that all my contributions will be made under the project's license
• [x] I have made a material change to the repo (functionality, testing, spelling, grammar)
• [x] I have read the Contribution Guidelines and my PR follows them
• [x] I have titled the PR appropriately
• [x] I have updated my branch with the main branch
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] I have added the necessary documentation about the functionality in the appropriate .md file
• [x] I have added inline documentation to the code I modified

If you have questions, please file a support ticket.

[zwartho]

@twilio-dx what is the hold up on this PR? Go 1.17 is almost 2 years old at this point!

[marcoshuck]

@twilio-dx what is the hold up on this PR? Go 1.17 is almost 2 years old at this point!

+1

Would you consider creating a new PR with the latest versions included? I can give it a review!