This PR replaces the `copy_prs` functionality from the `ops-bot` with the new dedicated `copy-pr-bot` GitHub application.

Thorough documentation for the new `copy-pr-bot` application can be viewed below.

- https://docs.gha-runners.nvidia.com/apps/copy-pr-bot/

**Important**: `copy-pr-bot` enforces signed commits. If an organization member opens a PR that contains unsigned commits, it will be deemed untrusted and therefore require an `/ok to test` comment. See the GitHub docs [here](https://docs.github.com/en/authentication/managing-commit-signature-verification/about-commit-signature-verification) for information on how to set up commit signing.

Any time a PR is deemed untrusted, it will receive a comment that looks like this: rapidsai/ci-imgs#63 (comment).

Every subsequent commit on an untrusted PR will require an additional `/ok to test` comment.

Any existing PRs that have unsigned commits after this change is merged will require an `/ok to test` comment for each subsequent commit _or_ the PR can be rebased to sign the unsigned commits as mentioned in the docs here:
https://docs.gha-runners.nvidia.com/cpr/contributors.

This information is all included on the documentation page linked above.

_I've skipped CI on this PR since it's not a change that is tested._

[skip ci]

* rapids infra ci activation

* change name premerge

* Update docs theme to sphinx-book-theme

* Update sphinx book theme to 1.0.1

for python version 3.8 support

* Add env var for protocol buffers implementation

* Update versions of myst-nb and sphinx-external-toc for python 3.8

* Add sphinx_design dependency

* remove old html_sidebars from conf.py

* Add GDPR info to footer

Signed-off-by: Mike McKiernan <mmckiernan@nvidia.com>

* match changes from core/models

---------

Signed-off-by: Mike McKiernan <mmckiernan@nvidia.com>
Co-authored-by: Oliver Holworthy <1216955+oliverholworthy@users.noreply.github.com>

* allow cpp code path to be used for Categorify ops

* Update merlin/systems/workflow/base.py

* formatting

* spelling

* require env-variable opt-in tfor cpp code path

* Update merlin/systems/workflow/base.py

---------

Co-authored-by: Oliver Holworthy <oholworthy@nvidia.com>
Co-authored-by: Julio Perez <37191411+jperez999@users.noreply.github.com>