BaseTools: Support long file path in windows for misc functions

BaseTools: Support long file path in windows for misc functions

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2103

Current CopyFileOnChange() and SaveFileOnChange() in
BaseTools\Source\Python\Common\Misc.py don't use the dedicated
long file path API to handle the file path strings and cannot
support the long file path copy and save in windows. This patch
enhances them to support the long file path copy and save
correctly.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Bob Feng <bob.c.feng@intel.com>
Signed-off-by: Steven Shi <steven.shi@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>