program: Port over history from SPL

[joncinque]

Problem

It's time to move over the SPL program implementations to their specific repos, but it hasn't been done.

Summary of changes

Following the PR for the stake interface at solana-program/stake#12, but for SPL. I ran:

# add the remote for the source repo
git remote add spl https://github.com/solana-labs/solana-program-library.git
# fetch the master from spl under a different local branch
git fetch spl master:fromspl
git switch fromspl
# be safe, remove the remote
git remote rm spl
# filter the stake related files
python3 ../../git-filter-repo \
                                 --path memo/program/src/entrypoint.rs \
                                 --path memo/program/src/lib.rs \
                                 --path memo/program/src/processor.rs \
                                 --path memo/program/Cargo.toml \
                                 --path memo/program/tests/functional.rs \
                                 --path memo/program/README.md \
                                 --path-rename memo/program/src/entrypoint.rs:program/src/entrypoint.rs \
                                 --path-rename memo/program/src/lib.rs:program/src/lib.rs \
                                 --path-rename memo/program/src/processor.rs:program/src/processor.rs \
                                 --path-rename memo/program/Cargo.toml:program/src/Cargo.toml \
                                 --path-rename memo/program/tests/functional.rs:program/tests/functional.rs \
                                 --path-rename memo/program/README.md:program/README.md \
                                 --force
# NOTE: I got the destination for Cargo.toml wrong, so had to git mv it afterwards
# re-add this repo
git remote add origin git@github.com:joncinque/memo.git
git fetch origin main
git rebase main

[febo]

Looks great! Just a tiny nit on your "script" comments:

# fetch the master from agave under a different local branch

Probably you meant "from spl".

[joncinque]

I sure did -- thanks!