Updates Porkbun, DuckDNS & Azure challenge providers

[chaptergy]

• Adds Porkbun as a DNS challenge provider, which resolves Porkbun as DNS provider #1079.

• Updates the DuckDNS certbot plugin which is actually compatible with NPM, see Support credentials file infinityofspace/certbot_dns_duckdns#15.

• Reactivates and updates Azure dns provider to fix Azure DNS challenge fails #1087

• Dns challenge providers are now displayed in alphabetical order.

[jc21]

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Docker Image for build 2 is available on DockerHub as jc21/nginx-proxy-manager:github-pr-1099

Note: ensure you backup your NPM instance before testing this PR image! Especially if this PR contains database changes.

[jc21]

This is an automated message from CI:

Docker Image for build 3 is available on DockerHub as jc21/nginx-proxy-manager:github-pr-1099

Note: ensure you backup your NPM instance before testing this PR image! Especially if this PR contains database changes.

[jc21]

This is an automated message from CI:

Docker Image for build 5 is available on DockerHub as jc21/nginx-proxy-manager:github-pr-1099

Note: ensure you backup your NPM instance before testing this PR image! Especially if this PR contains database changes.