feat: add plugin build command (#10935)

Fixes: FRMW-2863

Adds the `plugin:build` command that is used to compile the source code of a plugin for publishing it to a package registry. The command is similar to the `build` command, except it does not copy the `package.json` and the `lock` files to the build output

packages/core/framework/src/build-tools/compiler.ts

@@ -382,8 +382,55 @@ export class Compiler {
     }
   }
 
-  // @todo
-  buildPluginBackend() {}
+  /**
+   * Compiles the plugin source code to JavaScript using the
+   * TypeScript's official compiler
+   */
+  async buildPluginBackend(tsConfig: tsStatic.ParsedCommandLine) {
+    const tracker = this.#trackDuration()
+    const dist = ".medusa/server"
+    this.#logger.info("Compiling plugin source...")
+
+    /**
+     * Step 1: Cleanup existing build output
+     */
+    this.#logger.info(
+      `Removing existing "${path.relative(this.#projectRoot, dist)}" folder`
+    )
+    await this.#clean(dist)
+
+    /**
+     * Step 2: Compile TypeScript source code
+     */
+    const { emitResult, diagnostics } = await this.#emitBuildOutput(
+      tsConfig,
+      ["integration-tests", "test", "unit-tests", "src/admin"],
+      dist
+    )
+
+    /**
+     * Exit early if no output is written to the disk
+     */
+    if (emitResult.emitSkipped) {
+      this.#logger.warn("Plugin build completed without emitting any output")
+      return false
+    }
+
+    /**
+     * Notify about the state of build
+     */
+    if (diagnostics.length) {
+      this.#logger.warn(
+        `Plugin build completed with errors (${tracker.getSeconds()}s)`
+      )
+    } else {
+      this.#logger.info(
+        `Plugin build completed successfully (${tracker.getSeconds()}s)`
+      )
+    }
+
+    return true
+  }
 
   /**
    * Compiles the backend source code of a plugin project in watch