- Adds `ExtismContext` instead of global `PLUGINS` registry
- Adds `extism_context_new`, `extism_context_free` and
`extism_context_reset`
- Requires updating nearly every SDK function to add context parameter
- Renames some SDK functions to follow better naming conventions
- `extism_plugin_register` -> `extism_plugin_new`
- `extism_output_get` -> `extism_plugin_output_data`
- `extism_output_length` -> `extism_plugin_output_length`
- `extism_call` -> `extism_plugin_call`
- Updates `extism_error` to return the context error when -1 issued for
the plug-in ID
- Adds `extism_plugin_free` to remove an existing plugin
- Updates SDKs to include these functions
- Updates SDK examples and comments
Co-authored-by: Steve Manuel <steve@dylib.so>
