feat: rollup to libextism 1.9.1 (#32)

- [x] CompiledPlugin
 - [x] HTTP Response headers
 - [x] Call with Host Context
 - [x] Fuel limit support
 - [x] Update docs
 - [x] Add tests
 - [x] Check for backward compatibility

refactor: phpcs and composer related updates (#21)

Hey there,

I know this looks huge, but as far as I can see, there are no standards
in the PHP code. I thought I might add some standards to make the PHP
SDK more collaborative for everyone. If you think these changes are too
much, I wouldn't mind creating multiple PRs for a smoother transition.

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Co-authored-by: Muhammad Azeez <muhammad@dylibso.com>

feat: add Host Functions support (#13)

Fixes #11 

 - [x] Implement FFI calls
 - [x] Implement CurrentPlugin
 - [x] Implement HostFunction
 - [x] Fail fast when validating callback params
 - [x] Add PHPDoc comments
 - [x] Add README section
 - [x] Add tests
 - [x] Review for breaking changes
- [ ] ~~User Data~~. Wasn't able to find a way to pin PHP objects and
get their address. Users can use captured variables in the callback
closures instead.

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Co-authored-by: Steve Manuel <steve@dylib.so>

chore: update composer.json for publishing