Plugins: Split WIT into three packages & Fixes

* Split WIT interface into three packages: (plugins, bytesource, shared)
  to generate the shared items once only and enable removing the
  features on the plugins-api crate since the bindings don't clash
  anymore.
* This separation changed the whole structure of the WIT files and
  made it similar to the structure of wasi crate.
* Generate unified bindings for the shared types and move all their code
  into the shared module in plugins-api crate.
* Adjust the unit tests for the macros accordingly, and remove all the
  wild card imports.
* Adjust example plugins and make then compile.
* Plugin host doesn't compile currently.
* Documentations in WIT and plagins-api still missing.

application/apps/indexer/plugins/file_source/src/lib.rs

@@ -9,11 +9,11 @@ use std::{
 };
 
 use plugins_api::{
-    bytesource::{
-        ByteSource, ConfigItem, ConfigSchemaItem, ConfigSchemaType, ConfigValue, InitError,
-        SourceConfig, SourceError, Version,
-    },
+    bytesource::{ByteSource, SourceConfig, SourceError},
     bytesource_export, log,
+    shared_types::{
+        ConfigItem, ConfigSchemaItem, ConfigSchemaType, ConfigValue, InitError, Version,
+    },
 };
 
 const INPUT_PATH_ID: &str = "input-path";