Revamp WillingToIssueWildcards to WillingToIssue. Remove the need for
identifier.ACMEIdentifiers in the WillingToIssue(Wildcards) method.
Previously, before invoking this method, a slice of identifiers was
created by looping over each dnsName. However, these identifiers were
solely used in error messages.
Segment the validation process into distinct parts for domain
validation, wildcard validation, and exact blocklist checks. This
approach eliminates the necessity of substituting *. with x. in wildcard
domains.
Introduce a new helper, ValidDomain. It checks that a domain is valid
and that it doesn't contain any invalid wildcard characters.
Functionality from the previous ValidDomain is preserved in
ValidNonWildcardDomain.
Fixes#3323
d281702c17