FileTarget: Fix continuous archiving bug.

[bhaeussermann]

Fixes #1124

The bug manifested since we were archiving based on the log file's creation time, but it seems to be caused by a strange anomaly with the Windows file system:
When we archive, the log file is moved to the archive file path. However, when the new log file is created, it ends up having the same creation time of the old log file (which is now archived).

Others have observed this behavior, and it turns out is caused by the Windows NT Tunneling capabilities which is meant to facilitate the safe saving mechanism of MS-DOS programs.

The fix is to manually set the creation time of the file when it is created.

[codecov-io]

Current coverage is 73.21%

Merging #1125 into master will increase coverage by +0.03% as of 7208d18

@@            master   #1125   diff @@
======================================
  Files          264     264       
  Stmts        14926   14924     -2
  Branches      1635    1634     -1
  Methods          0       0       
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+ Hit          10923   10927     +4
+ Partial        419     417     -2
+ Missed        3584    3580     -4

Review entire Coverage Diff as of 7208d18

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Uncovered Suggestions

1. +0.10% via ...nternal/AspHelper.cs#206...218
2. +0.10% via ...nternal/AspHelper.cs#188...200
3. +0.10% via ...nternal/AspHelper.cs#170...182
4. See 7 more...

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[304NotModified]

Thanks! Good work!