CLI - Replace clippy checks

[bfops]

Background

Clippy is slow. Since we really only use it for one things, we'd like to replace it with a "manual" search for the string println! and just warn about that.

Definition of Done

• Replace use of clippy with a text-based search for println! in the project (CLI - Replace clippy with a manual check #1928).
• Remove spacetimedb::println!, and other related macros (Remove IO macros #1929)
• Print a warning if the user passes --skip-println-checks (CLI - Replace clippy with a manual check #1928).

[bfops]

all linked PRs are done!