Implemented the customer installed-base view

src/features/install-base/action.js

@@ -0,0 +1,53 @@
+function createInstallBaseAction({ messageTypes, requestConsumerTokenServiceOnce, sendRuntimeMessage,
+  appendBackgroundRequestLog, openInstallBaseModal, environment }) {
+  const { document } = environment;
+  const pending = new Map();
+
+  async function load(partyNumber) {
+    const authorizations = await requestConsumerTokenServiceOnce();
+    const response = await sendRuntimeMessage({
+      type: messageTypes.requestInstallBase, partyNumber,
+      authorizations: { accountSummary: authorizations.accountSummary, installBase: authorizations.installBase }
+    });
+    appendBackgroundRequestLog(response?.debugRequests);
+    if (!response?.ok) throw new Error(response?.error || "Unable to load installed base.");
+    return response.items;
+  }
+
+  function createInstallBaseButton(opportunity) {
+    const button = document.createElement("button");
+    button.type = "button";
+    button.className = "opportunities-extension-action-button";
+    button.title = "View customer installed base";
+    button.setAttribute("aria-label", `View installed base for ${opportunity.CustomerAccount?.PartyUniqueName || "customer"}`);
+    const icon = document.createElementNS("http://www.w3.org/2000/svg", "svg");
+    icon.setAttribute("viewBox", "0 0 24 24");
+    icon.setAttribute("aria-hidden", "true");
+    icon.setAttribute("focusable", "false");
+    const path = document.createElementNS("http://www.w3.org/2000/svg", "path");
+    path.setAttribute("d", "M4 3h16v7H4z M4 14h16v7H4z M7 6.5h.01 M7 17.5h.01 M11 6.5h6 M11 17.5h6 M8 10v4 M16 10v4");
+    path.setAttribute("fill", "none");
+    path.setAttribute("stroke", "currentColor");
+    path.setAttribute("stroke-width", "1.7");
+    path.setAttribute("stroke-linecap", "round");
+    path.setAttribute("stroke-linejoin", "round");
+    icon.append(path);
+    button.append(icon);
+    button.addEventListener("click", async () => {
+      const view = openInstallBaseModal(opportunity, button);
+      const partyNumber = String(opportunity.CustomerAccount?.PartyNumber || "");
+      try {
+        if (!partyNumber) throw new Error("Customer Party Number is unavailable.");
+        if (!pending.has(partyNumber)) {
+          const request = load(partyNumber).finally(() => pending.delete(partyNumber));
+          pending.set(partyNumber, request);
+        }
+        view.render(await pending.get(partyNumber));
+      } catch (error) {
+        view.render([], error.message || "Unable to load installed base.");
+      }
+    });
+    return button;
+  }
+  return { createInstallBaseButton };
+}