Texbld

- Removed requests dependency
- Build as a .pyz file (no python dependencies)
- Build logs for images are shown
- Cleaner Resource schemes (github:owner/repo/branchconfigpath, local:packageconfigpath)
- Environmental variables (TEXBLD_CACHE, TEXBLD_PACKAGES)

- Container shows error logs
- Nix expressions for development

- Validation commands added
- Custom logging added (prettier error messages)
- Error handling added (including for TOML errors)
- Using Nix-inspired schemes for image names in the CLI instead of subparsers.
- FS access security vulnerability patched
- Utilities for pegging sha256 and revision of GitHub repositories.