Allow Vultr to set MTU and use as-is configs

[eb3095]

Proposed Commit Message

Allow Vultr to set MTU, accept-ra, routes, and use as-is configs

Add MTU, accept-ra, routes, options and a direct way to provide intact 
cloud configs for networking opposed to relying on configurations that 
may need changed often.

Additional Context

Our VPC project required a few more things than I was aware of . Sorry for the multiple PR's

Checklist:

• [ X ] My code follows the process laid out in the documentation
• [ X ] I have updated or added any unit tests accordingly
• [ X ] I have updated or added any documentation accordingly

[TheRealFalcon]

Looks good! My only comment is a minor naming issue.

[TheRealFalcon]

Thanks!

[TheRealFalcon]

FYI, travis is currently broken on main, so I won't be landing this PR until it is fixed. This has nothing to do with your PR. It should get fixed with #1043

[eb3095]

Yeah I saw that one last night. That's fine. I'll keep an eye on it and merge in main again when its in.