Remove previously implemented ContextAwarePluginInterface from FunctionCall(Interface/Base)

If someone implements FunctionCallInterface directly (without extending FunctionCallBase), they’ll need to provide their own implementations of normalize() and populateValues(). For example:

<?php

class CustomFunctionCall extends PluginBase implements FunctionCallInterface {

  public function populateValues(ToolsFunctionOutput $output) {
    // Custom logic without contexts.
    $this->configuration['values'] = $output->getArguments();
  }

  public function normalize(): ToolsFunctionInput {
    $function = new ToolsFunctionInput($this->getFunctionName(), []);
    $function->setDescription($this->pluginDefinition['description']);
    return $function;
  }
}

Code that interacts with FunctionCallInterface instances and expects context-related methods (e.g., getContextDefinitions()) should check if the plugin implements ContextAwarePluginInterface. For example:

if ($function_call instanceof ContextAwarePluginInterface) {
  $context_definitions = $function_call->getContextDefinitions();
  // Work with contexts...
} else {
  // Handle context-free plugin...
}

Looks good to me.