test-backend-ops: allow loading tests from file and parsing model operators into...

test-backend-ops: allow loading tests from file and parsing model operators into file (#19896)

* tests: allow loading test-backend-ops tests from json

* add error threshold based on op

* add error when file cannot be read

* add graph operator json extraction tool

* add nb parameter for non-contiguous input tensors

* fix view check

* only use view if non-contiguous/permuted, use C++ random instead of rand()

* replace internal API calls with public llama_graph_reserve call

* reduce test description length

* fix nb[0] not getting set for view

* add name to tests

* fix inplace error

* use text file instead of json

* move llama_graph_reserve function to new llama-ext header, move export-graph-ops to tests/

* fix missing declaration

* use pragma once

* fix indent

* fix Windows build