[Support] Use all_read | all_write for createTemporaryFile (#83360)

In a04879ce, dsymutil switched from using TempFile to
createTemporaryFile. This caused a regression because the two use
different permissions:

 - TempFile opens the file as all_read | all_write
 - createTemporaryFile opens the file as owner_read | owner_write

The latter turns out to be problematic for dsymutil because it either
promotes the temporary to a proper output file, or it would pass it to
`lipo` to create a universal binary and `lipo` preserves the permissions
of the input files. Either way, this caused issues when the build system
was run as a different user than the one ingesting the resulting
binaries.

I did some version control archeology and I couldn't find evidence that
these permissions were chosen purposely. Both could be considered
reasonable default.

This patch changes the permissions to `all read | all write` to make the
two consistent and match the one currently used by the higher level
abstraction (TempFile).

rdar://123722848