improvement: refactor Operation component structure (via #4686)

...into OperationSummary, OperationSummaryPath, OperationSummaryMethod

src/core/components/operation-summary-method.jsx

@@ -0,0 +1,25 @@
+import React, { PureComponent } from "react"
+import PropTypes from "prop-types"
+import { Iterable } from "immutable"
+
+export default class OperationSummaryMethod extends PureComponent {
+
+  static propTypes = {
+    operationProps: PropTypes.instanceOf(Iterable).isRequired,
+    method: PropTypes.string.isRequired,
+  }
+
+  static defaultProps = {
+    operationProps: null,
+  }
+  render() {
+
+    let {
+      method,
+    } = this.props
+
+    return (
+      <span className="opblock-summary-method">{method.toUpperCase()}</span>
+    )
+  }
+}