TXT records without quotation marks ignore content after first whitespace

[tquensen]

For a TXT record like example.org. TXT 300 v=spf1 mx include:spf.example.com -all the parser ignores the content after the first space.

TXT records are allowed to have multiple "character strings" so this behaviour is valid

I replaced the fromText method to resolve the issue. This also fixes content with multiple quoted strings, like "foo bar" "foo baz"

public function fromText(string $text): void
			{
				$string = new StringIterator($text);
				$txt = new StringIterator();

				while ($string->valid()) {
					if ($string->is(static::WHITESPACE)) {
						$string->next();
						continue;
					}

					if ($string->is(Tokens::DOUBLE_QUOTES)) {
						self::handleTxt($string, $txt);
						$string->next();
						$txt->append(' ');
						continue;
					}

					static::handleContiguousString($string, $txt);
					$string->next();
					$txt->append(' ');
				}

				$this->setText(trim((string) $txt), true);
			}

[samuelwilliams]

What test cases need to be added?