chore: add scripts to help with repo management

[zshipko]

• Moves the version of the extism command into its own file: extism/VERSION
• Adds ./scripts/set-version.sh to set the version for the extism command
  • Usage: ./scripts/set-version.sh 0.3.9
• Adds ./scripts/release.sh to create a new release using the current extism version
  • Usage: ./scripts/release.sh
• Adds ./scripts/update-deps.sh to update all depdendencies
  • Usage: ./scripts/update-deps.sh
• Adds ./scripts/update-extism-cli.sh to update cli dependency in extism and extism-dev
  • Usage: ./scripts/update-extism-cli.sh