webapp: Added --port option, and annex.port config

The getSocket comment that mentioned using ":port"
in the hostname seems to have been incorrect or be out of date.
After all, the bug report came when the user first tried doing that,
and it didn't work.

Sponsored-by: the NIH-funded NICEMAN (ReproNim TR&D3) project

doc/bugs/webapp_--listen_port_is_not_used__63__.mdwn

@@ -19,3 +19,5 @@ git-annex version: 10.20230126
 
 [[!meta author=yoh]]
 [[!tag projects/repronim]]
+
+> [[done]] --[[Joey]]

doc/bugs/webapp_--listen_port_is_not_used__63__/comment_4_ba217465bfa738b77ea9417a33810d75._comment

@@ -0,0 +1,22 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 4"""
+ date="2024-01-25T17:29:08Z"
+ content="""
+I found an old todo about the same thing,
+[[todo/Make_webapp_port_configurable]].
+
+The idea there was, they were using docker and wanted to open only a
+specific port selected for the webapp. So basically the same kind of thing.
+
+I think that this should be a separate --port option, to avoid needing to
+try to parse something that may be an ipv6 address or hostname, or
+whatever.
+
+I don't think that using --port should prevent the webapp from needing
+the `?auth=' part of the url, as output when using --listen.
+
+Probably it does not make sense to use --port without also using --listen,
+but if the user does use it, I don't think --port needs to output the url
+the way --listen does.
+"""]]

doc/bugs/webapp_--listen_port_is_not_used__63__/comment_5_99a6933f30649bc33ee5c74b33fc7046._comment

@@ -0,0 +1,7 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 5"""
+ date="2024-01-25T18:06:15Z"
+ content="""
+Implemented --port.
+"""]]