[roll] Roll fuchsia [gn_desc] Add gn_desc cli tool

Adds the gn_desc cli tool that can parse gn's desc json
output, and provide a faster query method than re-running
all of GN for every query.

To use, add '//tools/gn_desc' to your host_tools list, or
use '--with-host //tools/gn_desc', followed by:
'fx build host-tools/gn_desc'

This will compile the tool, and run GN to create an
'<outdir>/gn_desc.json', which can then be used with
the tool to find targets:

fx gn_desc -v <outdir>/gn_desc.json match <foo> list

which will print out a list of targets that match the
regex <foo>.

Targets can be selected with:
- match -> regex on the target label
- match-file -> regex on the input and/or output files
- label -> an exact GN target (with toolchain if not default)

Then the commands for displaying the selected targets are:
- list -> the target's label
- summarize -> similar to gn desc, but with more control over
the outputs.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/810736
Original-Revision: 65fbfff5a7be8974f475134c0233b7e687beea2c
GitOrigin-RevId: f3d80f5bfae70cb7438d4d16ad2a539640bfc852
Change-Id: I827e617cd9dbb080ef4aacb900184dbafcd000bb