[fix] [broker] No longer allow creating subscription that contains slash

[poorbarcode]

Motivation

Topic name rule

• old version: {tenant}/{cluster}/{namespace}/{topic}/{subscription}
• new version: {tenant}/{namespace}/{topic}/{subscription}

There are many HTTP APIs defined as HTTP Method {topic name}/{subscription name}

If a subscription contains /, the broker will assume it is a topic created with the old rule, then users will get a cluster does not exist error or a topic not found error

Modifications

No longer allow creating a subscription that contains a slash

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository: x

[gaoran10]

LGTM.

Do we need to support decoding URL-encoded subscription names in broker side? Thus users can use existing URL-encoded subscription names in HTTP requests.