Allow specification of the exact API URL via new option --api

[darkexplosiveqwx]

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What does this PR aim to accomplish?:

Allows SERVER to be the full API path, eliminating the need for the extra DNS lookup.
This also allows multiple APIs on the same server (like https://pi.hole/pihole1/api and https://pi.hole/pihole2/api).
PADD will still work even if the DNS record doesn't work.

This fixes my original problem I specified on discourse

How does this PR accomplish the above?:

Check if SERVER starts with https:// or http:// and sets chaos_api_list to SERVER.

Link documentation PRs if any are needed to support this PR:

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[yubiuser]

I'm thinking we probably should add a new option/flag like --api where users can specify the api URL. I'm not sure mixing the URL with the server domain/IP is desirable. And we should make it clear that this is an advanced feature most users probably never need.

[darkexplosiveqwx]

This is a good Idea and will also avoid potential issues with the functionality I introduced in #450, since it assumes SERVER is an IP.