[RFC] cachemgr style updates

I've been looking way ahead and considering the design changes we would
need to upgrade the cachemgr reports to browsable HTML content. Stuff
beyond the simple table conversion currently done by cachmgr.cgi.

This will all depend on the internal server feature completion, as well
as the visible_hostname / unique_hostname reworking. So will be 3.3
release at the earliest.

Access:

  * via http://$visible_hostname/ or http://$unique_hostname/ requests
intercepted by the internal server feature. Also https:// if SSL/TLS
available.

  * Splitting the manager access out into a manager_access directive ACL
checklist.
   Thus ACL restrictions and authentication becomes via real HTTP auth
process same as http_access. Without limits like only checking the
password or only one password per action/report.

Formats and Encoding:

  We will have to support the old cachemgr.cgi and squidclient requests
for some time. Which means we will have to support multiple output
formats in the cachemgr reports.

  * register the output types supported by the component as a parameter
during the registration action. So we can specify TXT, HTML, XML or any
other file formats which the report can be delivered in. Default to
start with just being TXT.

  * Using the URL filename portion to encode the type of report.
   Alternative content formatting would appear under /.../action.html or
/.../action.xml etc.
   The old API just requests /.../action as the path. So this can be
mapped to produce the old TXT format also available as /.../action.txt.
   ** as a bonus "squidclient mgr:action.txt" could be requested
already. Making that interface somewhat forward-compatible.
   ** cachemgr.cgi is obsolete with this feature so does not matter.

Nothing unusual there from the user perspective. I hope.

Navigation display:

  * placing the "menu" report permanently off to one side of each page
for quick linking in HTML format.

  * some type of group or category as part of the component report
registration.
   This would be used to produce the side menu in a short form with
expandable groups.

  * URL linking for configured non-origin peers to their cachemgr pages.
   Thus forming a navigable hierarchy "website" for managing clusters.
   Similar report for workers in SMP mode, with additional URL details
to specify individual worker reports where appropriate.

Amos

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