rename `install` to `upload`; alias as `install`

[chadoh]

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In the XDR & SDK, the operation is called upload.

"Upload" makes more sense with most people's mental model, too. From the perspective of the person issuing the command, they are uploading something to the blockchain. Only from the perspective of the blockchain itself does it make sense to think of it as an "upload."

Let's rename the command. To avoid breaking the numerous scripts and docs that refer to the old name, let's alias it with the old install name. We can keep the alias around indefinitely.