🐛 `QUOTA` support is broken for types other than `STORAGE`

Support for the QUOTA extension is broken in several ways: it assumes STORAGE is the only possible quota resource type (which was not true, even for RFC2087) and the response parser will crash the connection if multiple resource types are returned. Fixing this is backward incompatible, so it will need to be hidden behind new config attribute.

Response Parser

Currently, the response parser for quota-response only allows zero or one quota-resource. It implicitly assumes that resource type is STORAGE, so it doesn't store the resource type. And it crashes for more than one resource type.

• QUOTA response should be parsed consistently with RFC2087 and RFC9208, into a new QuotaResponse type.

Response Data

MailboxQuota must be deprecated: the #mailbox attribute is misleadingly named (it should be #quota_root), the class is misleadingly named (again: it provides information about a "quota root", which does not have a 1-to-1 relationship with mailbox), and it can only list usage and limit for a single resource type

• QuotaResponse = Data.define(:quota_root, :resources)
  • #to_deprecated_mailbox_quota for backwards compatibility
• QuotaResponse::Resource = Data.define(:name, :usage, :limit)

Net::IMAP command methods

• #getquota: Use use_deprecated_mailbox_quota config:
  • when :silent, return only the STORAGE resource (nil if no STORAGE resource)
  • when true, same as :silent but issue a warning for non STORAGE resource types
  • when false, return QuotaResponse rather than MailboxQuota
• #getquotaroot: Use use_deprecated_mailbox_quota config (same as #getquota)
• #setquota: support any number of any resource types via *rest args

Additional

Separately from this bug, there are some other QUOTA related issues (TODO: move these to separate issues/PRs):

• RFC9208 support
  • new capabilities: QUOTA=RES-* and QUOTASET
    • document at class level, and on all three quota methods
  • QuotaResponse: Add accessors "attributes" for every type in the IANA quota resource type registry:
    • def storage = resources.find { "STORAGE".casecmp?(it.name) }
    • def message = resources.find { "MESSAGE".casecmp?(it.name) }
    • def mailbox = resources.find { "MAILBOX".casecmp?(it.name) }
    • def annotation_storage = resources.find { "ANNOTATION-STORAGE".casecmp?(it.name) }
  • new response code: OVERQUOTA
    • document on ResponseCode class
    • add (trivial) support in response parser
  • #setquota:
    • support IANA-registered resource types via keyword args
• #getquotaroot:
  • Rather than return an array of mixed MailboxQuotaRoot and QuotaResponse objects, return a single hash-like object that combines them.
    • Config#getquotaroot_returns_quotaroot_data
  • Config#setquota_returns_quota_responses => return matching untagged QUOTA responses

Start with the quota-response parser and the Net::IMAP #getquota, #getquotaroot, and #setquota entry points, using RFC2087 and RFC9208 as the protocol references. Done means multiple resource types parse without crashing, QuotaResponse and backward-compatible behavior are supported through configuration, and quota setting accepts the requested resource types.