Fixes

• nvm_download: ensure all args are quoted
• --save: avoid a conflict with set -e
• nvm_has_colors: avoid an aliased tput
• declare an unbound variable
• nvm install -b: do not attempt to download source on a failed binary download with -b
• nvm install -b: when no binary is available, fail and output a clear message

Refactors

• --save: clean up some usage
• install.sh: fix node capitalization

Tests

• set proper permissions on test files
• move sourcing suite to GHA
• fix nvm ls-remote unit test