Add Dockerfiles for Windows entrypoint and nop images

[aiden-deloryn]

Changes

This change adds two new Dockerfiles under 'images/windows/'. These
can be used to build Windows images for the entrypoint and nop
binaries. Docker is used to build these images because Ko does
not currently support building for Windows.

Related issue: #3951

/kind misc

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Release Notes

NONE

[tekton-robot]

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[aiden-deloryn]

/assign @pritidesai

[pritidesai]

/ok-to-test

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[imjasonh]

/lgtm