[proof-manager-cli] Rename the proof-manager executable to proof-manager-cli

Summary: This is more in line with the naming convention and so far there is no gui anyway.

Test Plan:

cd apps/proof-manager-cli
cargo build --release

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D18956