sbox: run commands using script for large commands

Linux has limit of 32 pages for a single argument. Sbox's method of
handling commands as a single large string can run into this limitation.

Write the large command to a script file and then execute that file.
This better accommodates the large commands, and leaves a script in the
temporary directory useful for manual inspection if necessary.

Bug: 177070955
Bug: 174232579
Fixes: 202297224
Test: m
Test: make particular target with very long command exceeding limit.
Change-Id: Ia298fdfd7a759821c37f540deaf800026041e511