🚸 ux(templating): add templates

[jfbus]

Description

This PR adds templating.

The request is built from the template and from flags.

Template from stdin:

echo '{"NetId":"vpc-foo"}' | gli oapi CreateSubnet --IpRange 10.0.1.0/24

Template from a file:

gli oapi CreateSubnet --IpRange 10.0.1.0/24 --template subnet.json

Type of Change

Please check the relevant option(s):

• 🐛 Bug fix
• ✨ New feature
• 🧹 Code cleanup or refactor
• 📝 Documentation update
• 🔧 Build or CI-related change
• 🔒 Security fix
• Other (specify):

How Has This Been Tested?

Please describe the test strategy:

• Manual testing
• Unit tests
• Integration tests
• Not tested yet

Checklist

• I have followed the Contributing Guidelines
• I have added tests or explained why they are not needed
• I have updated relevant documentation (README, examples, etc.)
• My changes follow the Conventional Commits specification
• My commits include appropriate Gitmoji

Additional Context