* Remove reference to removed dir 'third_party/rust_crates'.
* Remove reference to unused environment variable 'DENO_NINJA_PATH'.
* Remove helper functions 'root()' and 'tp()'.
* Move definition of 'third_party_path' to build.py.
* Move definition of 'gn_exe()' to setup.py.
* Move 'download_sccache()' and 'download_hyperfine()' from prebuilt.py
to third_party.py, and delete prebuilt.py.
* Add helper function 'get_platform_dir_name()' to locate the
platform-specific 'v8/buildtools/<platform>' and
'prebuilt/<platform>' directories.
* Add helper function 'get_prebuilt_tool_path()' that returns the full
path to a platform-specific executable in //prebuilt.
* Cosmetic improvements.
Fixes some sed errors introduced in c43cfe.
Unfortunately moving libdeno required splitting build.rs into two parts,
one for cli and one for core.
I've also removed the arm64 build - it's complicating things at this
re-org and we're not even testing it. I need to swing back to it and get
tools/test.py running for it.
* Changed tools/lint.py to lint the entire js and tests directorys and sub directories, currently it was pointing at tsconfig and would only lint files that were part of js/main.ts or node_modules/typescript/lib/lib.esnext.d.ts and their dependencies
* Broke the typescript linting out into separate steps for the main typescript programing and tests.
* Fixed linting issues in ts tests.
