This bootstrap script will allows us to have a stable environment
across all bots runnning toolchain scripts.
The basics of this script is that we can chain it with the toolchain
ones, and it takes care that we have a valid `vpython` install to run
our tools on. It is possible to use both a url to download a script, or
to provide a local one.
This is being done to correct some of the issues we are having in CI
with python deps, but it will also permit us to come up with subrevision
schemes for toolchains that take into account the hashing of the
builder.
Bug: https://github.com/brave/brave-browser/issues/55812
cdesouza-chromium
a7cb22bb67