Add support for Name.com

[giuseongit]

Name.com API docs: https://www.name.com/api-docs/DNS

This is a follow-up of #507. I've worked an all the comments except for #507 (comment) and #507 (comment).
I've seen that the tests are slightly changed, so I've fixed that too.

pinging @adferrand as he was the reviewer of the previous pr

[adferrand]

Hello @giuseongit, do you need some help to troubleshoot the test failures on Python 3.7?

[giuseongit]

@adferrand yes please, I thought that changing some tests could resolve this issue, but I cannot make the tests pass

[adferrand]

No big deal, the internals of unittest.mock have changed between Python 3.7 and 3.9. It is better to use unitest.mock.call to check mocked calls since the class will cover this discrepencies in term of implementation for you.

[adferrand]

I can live with the internal http session in the provider. LGTM!