Add shellcheck to CI and a progress bar for `sed`'ing in `genbindings.sh`#127

tnull wants to merge 5 commits intolightningdevkit:mainlightningdevkit/ldk-c-bindings:mainfrom

tnull:2024-06-shellcheck-and-progresstnull/ldk-c-bindings:2024-06-shellcheck-and-progressCopy head branch name to clipboard