Do some cleanup on TimeSpan to ensure better inlining and clearer semantics

[tannergooding]

As per the title, this does some cleanup of TimeSpan to more consistently use throw helpers, to more consistently use named constants for important values, and to ensure that the implementation lives in the operators so less inlining is needed in the common case.

[tannergooding]

Some of this will allow constants to be folded for #94143 if we went with the following implementation:

public static TimeSpan FromHours(int hours, long minutes = 0, long seconds = 0, long milliseconds = 0, long microseconds = 0)
{
    return FromHours(hours)
         + FromMinutes(minutes)
         + FromSeconds(seconds)
         + FromMilliseconds(milliseconds)
         + FromMicroseconds(microseconds);
}

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Issue Details

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As per the title, this does some cleanup of TimeSpan to more consistently use throw helpers, to more consistently use named constants for important values, and to ensure that the implementation lives in the operators so less inlining is needed in the common case.

Author:	tannergooding
Assignees:	tannergooding
Labels:	area-System.DateTime
Milestone:	-

[tarekgh]

LGTM. thanks for cleaning this up!

[danmoseley]

just curious, you could have used >>> instead of >> here, right? then it would only be the low order bit holding the sign. does it make any difference to perf?

[tannergooding]

Signed and unsigned shift have the same cost in x64 and Arm64 hardware, so no real difference