New Feature: HASH() adds hashing functions to dnsconfig.js language

[fuero]

Having access to SHA1 would be great when managing catalog zones:

foo_name_suffix = HASH("sha1", "foo.name") + "zones"
D("catalog.example!int"
    , REG_NONE
	, DnsProvider(my_pdns_int)
    , TXT("version", "2")
    , PTR(foo_name_suffix, "foo.name.")
    , A("primaries.ext." + foo_name_suffix, "192.168.1.1")
)

So this PR adds a HASH function to Javascript following the above example.

[tlimoncelli]

Sounds like a reasonable feature to add.

Some changes I'd like to see in the PR:

• Move hashFunc to a separate file (hash.go)
• Add user-facing documentation? (https://docs.dnscontrol.org/developer-info/styleguide-doc#how-to-add-a-new-page)

[fuero]

Thanks for the feedback, I've added your suggestions.

[tlimoncelli]

Looks great! Thanks for the fast response.

Please run go generate ./... to regenerate the docs. (I forgot to mention that)

CC @cafferata to review the docs.

[cafferata]

CC @cafferata to review the docs.

@tlimoncelli, thanks for the mention.

@fuero, this new hash() function must be included within the table of content:

dnscontrol/documentation/SUMMARY.md

Lines 22 to 27 in 7b28609

	* [FETCH](language-reference/top-level-functions/FETCH.md)
	* [IP](language-reference/top-level-functions/IP.md)
	* [NewDnsProvider](language-reference/top-level-functions/NewDnsProvider.md)
	* [NewRegistrar](language-reference/top-level-functions/NewRegistrar.md)
	* [PANIC](language-reference/top-level-functions/PANIC.md)
	* [REV](language-reference/top-level-functions/REV.md)

[cafferata]

You could provide TypeScript autocomplete with the possible algorithm:

Suggested change

	algorithm: string
	algorithm: '"SHA1" | "SHA256" | "SHA512"'

[fuero]

@cafferata done, thanks!

[cafferata]

Great when feedback is processed so quickly. Thank you. If you would like to view the preview yourself, you can do so at the URL below:

https://docs.dnscontrol.org/~/revisions/4tbkwLMlJN3iIh1FDebG/language-reference/top-level-functions/hash

[tlimoncelli]

Looks good to me! Thanks for adding this feature!