feat(url): add API url for pi-hole API endpoints

  ## what
  - add API url for pi-hole API endpoints
  - endpoints
    - summaryRaw
    - summary
    - overTimeData10mins
    - topItems
    - topClients

  ## how
  - used web dev tools to reverse engineer what API calls were made
  - check reference https://discourse.pi-hole.net/t/pi-hole-api/1863

  ## why
  - These endpoints will be used to interact with pi-hole to get data
    and statistics

  ## where

  ## usage

src/utils/url/upstream.ts

@@ -0,0 +1,66 @@
+// upstream API obtained from
+// https://discourse.pi-hole.net/t/pi-hole-api/1863
+
+export const upstreamBaseApiUrl = '/api.php';
+
+// ////////////////////////////////////////////////////////////////////////////////////////////// //
+
+/**
+ * API url to fetch 'summaryRaw' to upstream API.
+ * Gives statistics in raw format (no number formatting applied).
+ *
+ * @remarks No Authorization required
+ * @see {@link ISummaryRaw} Data format returned
+ * @returns API URL for upstream API
+ */
+export const summaryRaw = () => `${upstreamBaseApiUrl}?summaryRaw`;
+
+// ////////////////////////////////////////////////////////////////////////////////////////////// //
+
+/**
+ * API url to fetch 'summary' to upstream API.
+ * Gives statistics in formatted style
+ *
+ * @remarks No Authorization required
+ * @see {@link ISummary} Data format returned
+ * @returns API URL for upstream API
+ */
+export const summary = () => `${upstreamBaseApiUrl}?summary`;
+
+// ////////////////////////////////////////////////////////////////////////////////////////////// //
+
+/**
+ * API url to fetch 'overTimeData10mins' to upstream API.
+ * Data needed for generating the domains/ads over time graph on the Pi-hole web dashboard
+ *
+ * @remarks No Authorization required
+ * @see {@link IOverTimeData10minutes} Data format returned
+ * @returns API URL for upstream API
+ */
+export const overTimeData10mins = () => `${upstreamBaseApiUrl}?overTimeData10mins`;
+
+// ////////////////////////////////////////////////////////////////////////////////////////////// //
+
+/**
+ * API url to fetch 'topItems' to upstream API.
+ * Data needed for generating the Top Domain and Top Advertisers Lists
+ *
+ * @remarks Authorization required
+ * @see {@link ITopItems} Data format returned
+ * @param numEntries - Number of entries to return. Default is 10
+ * @returns API URL for upstream API
+ */
+export const topItems = (numEntries = 10) => `${upstreamBaseApiUrl}?topItems=${numEntries}`;
+
+// ////////////////////////////////////////////////////////////////////////////////////////////// //
+
+/**
+ * API url to fetch 'getQuerySources' to upstream API.
+ * Data needed for generating the Top Clients list
+ *
+ * @remarks Authorization required
+ * @see {@link IGetQuerySources} Data format returned
+ * @param numEntries - Number of entries to return. Default is 10
+ * @returns API URL for upstream API
+ */
+export const topClients = (numEntries = 10) => `${upstreamBaseApiUrl}?topClients=${numEntries}`;