New provider and new registrar: hosting.de (#1041)

* Add http.net provider

* Rename httpnetProvider

* Add SSHFP capability

* Add paging for records

* Sort documentation notes alphabetically

* Add custom base URL

* Extend documentation for custom base URL

* - renamed to hosting.de
- Fix EnsureDomainExists
- GetNameservers read from NS Records

* Replaced http.net with hosting.de
Contributor Support from hosting.de

* baseURL for hosting.de in documentation
replaced %v with %w for errors
special handling for txt records using .TxtStrings

* removed last references to rc.Target
fixed Trim of last dot

* Re-engineer TXT records for simplicity and better compliance (#1063)

Co-authored-by: Tom Limoncelli <tlimoncelli@stackoverflow.com>
Co-authored-by: Oliver Dick <o.dick@hosting.de>
Co-authored-by: Oliver Dick <31733320+membero@users.noreply.github.com>

integrationTest/integration_test.go

@@ -926,6 +926,7 @@ func makeTests(t *testing.T) []*TestGroup {
 				//"MSDNS",     //  No paging done. No need to test.
 				//"AZURE_DNS", // Currently failing. See https://github.com/StackExchange/dnscontrol/issues/770
 				"HEXONET",
+				"HOSTINGDE",
 				//"ROUTE53", // Currently failing. See https://github.com/StackExchange/dnscontrol/issues/908
 			),
 			tc("1200 records", manyA("rec%04d", "1.2.3.4", 1200)...),