iceberg: rename to iceberg-cli

This conflicts with a cask named `iceberg`.[^1]

[^1]: https://github.com/Homebrew/homebrew-cask/blob/6b4a26d2bf1fbb07207917ed20121399c2c800e4/Casks/i/iceberg.rb

Author: carlocab

Formula/i/iceberg.rb

@@ -81,6 +81,7 @@
   "i386-elf-binutils": "x86_64-elf-binutils",
   "i386-elf-gcc": "x86_64-elf-gcc",
   "iccmax": "iccdev",
+  "iceberg": "iceberg-cli",
   "interactive-rebase-tool": "git-interactive-rebase-tool",
   "jfrog-cli-go": "jfrog-cli",
   "juju2": "juju",