Allow passing custom HTTPClient to HTTPUpdate (#4959)

This enables customizing HTTP headers which adds some extra flexibility.
This does not break anything of course because this change introduces a new constructor with a new additional HTTPClient argument for HTTPUpdate class.

libraries/HTTPUpdate/src/HTTPUpdate.cpp

@@ -58,6 +58,11 @@ HTTPUpdateResult HTTPUpdate::update(WiFiClient& client, const String& url, const
     return handleUpdate(http, currentVersion, false);
 }
 
+HTTPUpdateResult HTTPUpdate::updateSpiffs(HTTPClient& httpClient, const String& currentVersion)
+{
+    return handleUpdate(httpClient, currentVersion, true);
+}
+
 HTTPUpdateResult HTTPUpdate::updateSpiffs(WiFiClient& client, const String& url, const String& currentVersion)
 {
     HTTPClient http;
@@ -68,6 +73,12 @@ HTTPUpdateResult HTTPUpdate::updateSpiffs(WiFiClient& client, const String& url,
     return handleUpdate(http, currentVersion, true);
 }
 
+HTTPUpdateResult HTTPUpdate::update(HTTPClient& httpClient,
+        const String& currentVersion)
+{
+    return handleUpdate(httpClient, currentVersion, false);
+}
+
 HTTPUpdateResult HTTPUpdate::update(WiFiClient& client, const String& host, uint16_t port, const String& uri,
         const String& currentVersion)
 {

libraries/HTTPUpdate/src/HTTPUpdate.h

@@ -86,6 +86,10 @@ public:
 
     t_httpUpdate_return updateSpiffs(WiFiClient& client, const String& url, const String& currentVersion = "");
 
+    t_httpUpdate_return update(HTTPClient& httpClient,
+                               const String& currentVersion = "");
+
+    t_httpUpdate_return updateSpiffs(HTTPClient &httpClient, const String &currentVersion = "");
 
     int getLastError(void);
     String getLastErrorString(void);