feat: refactor and add ip saving

- clean up code to my new (and improved) standards
- print better miette diagnostigs for the error tests
- add an IP saving feature:
    save the last IP that successfully updated the records and usa that
    when restarting the service. This allows seamles upgrades of
    `webnsupdate` without having to manually trigger a DNS update

src/snapshots/webnsupdate__records__test__empty_label.snap

@@ -0,0 +1,16 @@
+---
+source: src/records.rs
+description: err
+expression: out
+---
+]8;;https://en.wikipedia.org/wiki/Fully_qualified_domain_name\(link)]8;;\
+
+  × empty label
+   ╭─[test_records_invalid:2:6]
+ 1 │ example.com.
+ 2 │ name..example.org.
+   ·      ▲
+   ·      ╰── label
+ 3 │ example.net.
+   ╰────
+  help: each label should have at least one character

src/snapshots/webnsupdate__records__test__hostname_too_long.snap

@@ -0,0 +1,16 @@
+---
+source: src/records.rs
+description: err
+expression: out
+---
+]8;;https://en.wikipedia.org/wiki/Fully_qualified_domain_name\(link)]8;;\
+
+  × hostname too long (260 octets)
+   ╭─[test_records_invalid:3:1]
+ 2 │ example.org.
+ 3 │ example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.example.net.
+   · ──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
+   ·                                                                                                                                   ╰── this line
+ 4 │ subdomain.example.com.
+   ╰────
+  help: fully qualified domain names can be at most 255 characters long

src/snapshots/webnsupdate__records__test__invalid_ascii.snap

@@ -0,0 +1,16 @@
+---
+source: src/records.rs
+description: err
+expression: out
+---
+]8;;https://en.wikipedia.org/wiki/Hostname#Syntax\(link)]8;;\
+
+  × invalid octet: '\xc3'
+   ╭─[test_records_invalid:2:19]
+ 1 │ example.com.
+ 2 │ name.this-is-not-aßcii.example.org.
+   ·                   ┬
+   ·                   ╰── octet
+ 3 │ example.net.
+   ╰────
+  help: we only accept ascii characters

src/snapshots/webnsupdate__records__test__invalid_octet.snap

@@ -0,0 +1,16 @@
+---
+source: src/records.rs
+description: err
+expression: out
+---
+]8;;https://en.wikipedia.org/wiki/Hostname#Syntax\(link)]8;;\
+
+  × invalid octet: ':'
+   ╭─[test_records_invalid:2:20]
+ 1 │ example.com.
+ 2 │ name.this-character:-is-not-allowed.example.org.
+   ·                    ┬
+   ·                    ╰── octet
+ 3 │ example.net.
+   ╰────
+  help: hostnames are only allowed to contain characters in [a-zA-Z0-9_-]

src/snapshots/webnsupdate__records__test__label_too_long.snap

@@ -0,0 +1,16 @@
+---
+source: src/records.rs
+description: err
+expression: out
+---
+]8;;https://en.wikipedia.org/wiki/Fully_qualified_domain_name\(link)]8;;\
+
+  × label too long (78 octets)
+   ╭─[test_records_invalid:2:6]
+ 1 │ example.com.
+ 2 │ name.an-entremely-long-label-that-should-not-exist-because-it-goes-against-the-spec.example.org.
+   ·      ───────────────────────────────────────┬──────────────────────────────────────
+   ·                                             ╰── label
+ 3 │ example.net.
+   ╰────
+  help: labels should be at most 63 octets

src/snapshots/webnsupdate__records__test__not_fqd.snap

@@ -0,0 +1,16 @@
+---
+source: src/records.rs
+description: err
+expression: out
+---
+]8;;https://en.wikipedia.org/wiki/Fully_qualified_domain_name\(link)]8;;\
+
+  × not a fully qualified domain name
+   ╭─[test_records_invalid:3:11]
+ 2 │ example.org.
+ 3 │ example.net
+   ·           ┬
+   ·           ╰── last character
+ 4 │ subdomain.example.com.
+   ╰────
+  help: hostname should be a fully qualified domain name (end with a '.')