This PR introduces the YAML frontend for plaster that is meant to
eventually become the only frontend, once all `.toml` Plaster files are
migrated.
This change covers all places where the assumption about `.toml` files
was being used, inclusing `brockit`, and `git-cr` tools.
Most of the code that should be deleted in the future is well guarded
with comments leading back to the issue tracking, so the TOML parser can
be dropped eventually.
With this change, a dependency to `pyyaml` has been introduced. This
dependency has wheels provided by `vpython`, which is already the
expected python runtime for Plaster.
- Rationale for this change
We have experimented at length with `.toml` files, in order to
understand some of the shortcomings they have that would be addressed
with `.yaml` files.
* `prettier` offers YAML formatting out-of-the-box. On the other hand,
formatters for TOML files are not easy to find, as both `prettier`
and `vpython` have their own challanges with the current options
* YAML's sytanx works better with codeblocks, as it doesn't require
quoting. This makes the content seen less noisy. Looking on some of
the migrated plasters, the YAML substitutions look more readable.
* YAML has better sytanx highlight support in some editors.
Bug: https://github.com/brave/brave-browser/issues/55738
cdesouza-chromium
a651e03a79