SocketsHttpHandler is inconsistent with header value trimming on HTTP/1.1

[MihaZupan]

From #74393 (comment)

The spec defines field lines as

  field-line   = field-name ":" OWS field-value OWS
  OWS          = *( SP / HTAB )

We currently trim leading SP and HTAB, but only trailing SP.
It should be much more common to encounter an HTAB before the value (following the name:), as there usually isn't any whitespace after the value.

Do we care about this inconsistency?
Filing this so we can make a conscious decision we can point to in the future.

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Issue Details

---

From #74393 (comment)

The spec defines field lines as

  field-line   = field-name ":" OWS field-value OWS
  OWS          = *( SP / HTAB )

We currently trim leading SP and HTAB, but only trailing SP.
It should be much more common to encounter an HTAB before the value (following the name:), as there usually isn't any whitespace after the value.

Do we care about this inconsistency?
Filing this so we can make a conscious decision we can point to in the future.

Author:	MihaZupan
Assignees:	-
Labels:	area-System.Net.Http
Milestone:	-

[karelz]

Triage: Should be simple - match one skipping of whitespaces with the other one.
Not critical, but we would welcome PR.