This will make it easier to support both string types at the same time
while we convert code, and tracking down remaining uses.
One big exception is Value::to_string() in LibJS, where the name is
dictated by the ToString AO.
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).
No functional changes.
For example, with this input:
```xml
<C>]]>
```
After seeing `<C>`, the parser will start parsing the content of the
element. The content parser will then parse any character data it sees.
The character parser would see the first two `]]` and consume them.
Then, it would see the `>` and set the state machine to say we have
seen this, but it did _not_ consume it and would instead tell
GenericLexer that it should stop consuming characters. Therefore,
we only consumed 2 characters.
Then, it would see that we are in the state where we've seen the
full `]]>` and try to take off three characters from the end of the
consumed input when we only have 2 characters, causing an assertion
failure as we are asking to take off more characters than there really
is.
Currently this can parse XML and resolve external resources/references,
and read a DTD (but not apply or verify its rules).
That's good enough for _most_ XHTML documents as the HTML 5 spec
enforces its own rules about document well-formedness, and does not make
use of XML DTDs (aside from a list of predefined entities).
An accompanying `xml` utility is provided that can read and dump XML
documents, and can also run the XML conformance test suite.
