Support using named pipes for manifests

[duggaraju]

System info

Operating System: Any
Shaka Packager Version: v2.6.1-634af65-release

Issue and steps to reproduce the problem

Try running a shaka command line with using a named pipe for the manifest name.

Packager Command:

Extra steps to reproduce the problem?
shaka writes the manifest to a temporary file and then renames. This would break the pipe.
When creating VOD content where manifest is written once at the end, can we avoid the rename and directly write to output to make it work with pipes?

What is the expected result?
the operation succeeds.

What happens instead?

The operation fails because the pipe is deleted during the rename. Also on windows named pipes are under \.\pipe directory so can't create a temporary file there.

[duggaraju]

On further investigation this issue seems to be specific to dash manifest. HLS manifests can be written to a pipe without issues.