SOLR-6994: Implement Windows version of bin/post

[janhoy]

Very much work in progress

[ashah2012]

When will this be released ? Any way to use this now ?

[janhoy]

Hmm, completely forgot that I worked on this :)
This is more than just a post.cmd, it is a refactor of post CLI into a Java program to be used both by post and post.cmd. Feel free to contribute :-)

[janhoy]

I'l not work more on this, at least not for 8x line. Closing PR. If anyone wants to pick up the work on 9x then I'll leave the branch around for some while.

[epugh]

out of curiosity, if this had been bin/solr post and post was just another Tool, would that have simplified this? So bin/solr.cmd post, so we don't add another Unix/Windows specific file????

[itygh]

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[janhoy]

That's a fine idea. A PostTool which calls the SimplePostTool API. We could keep bin/post as a wrapper?