build: ota: Support for install tools in /tmp/install

 * Anything in OUT/install gets packaged up into the zip and extracted
   to /tmp/install immediately after FullOTA_InstallBegin.

 * Use /tmp/install in edify scripts and remove code related to using
   and manipulating /system for install tools.

 * Modified to support signing steps being split from build steps.

   Package install files into target-files INSTALL path
   Read from target-files for OTA package creation

   From Change-Id: I64f919c2a757b5474f6cc5f82bd6c33c2a8b558a

 * This also fully reverts commit 6a324ba5 and partially reverts
   commit f388104e as the functions are still needed here.

   From Change-Ids: I4911244ec9945d197d2b56d0d11eab6d2f7b6d3e
                    I4943e2e89ee5c810a63746c570dc5e31e95b8c53

Squashed with the following:

Author: LuK1337 <priv.luk@gmail.com>
Date:   Wed Feb 19 02:14:59 2020 +0100
    releasetools: Use 0oXXX instead of 0XXX for octal

    * Fixes py3 syntax error.

    Change-Id: Ia9ca6e392f43694ddf4c952b07bf159e8dead36e

Author: LuK1337 <priv.luk@gmail.com>
Date:   Fri Nov 13 15:27:24 2020 +0100
    Add $(PRODUCT_OUT)/install to INTERNAL_RECOVERYIMAGE_FILES

    * Fixes $(PRODUCT_OUT)/install not being included on targets
      not providing their own /vendor || /system/vendor.

    Change-Id: I15b8305bb7efacfcf3018708bf7ff8b8500744fb

Change-Id: I315a3238e36c8d15e26f935e272f7e27dd59c320