[4.1] Add server timing response header in debug mode

[laoneo]

Summary of Changes

Browsers do support a server timing header field which adds information what happens on the server side. This basically gives the developer insight what happens in the "Time to First Byte".
This pr adds the missing header in the debug plugin, as this header should not be added when in production mode because of performance reasons.

Would be nice to get some feedback about spicing up the values of the header as currently I'm just logging them as they are.

The view looks like in the following picture:

Testing Instructions

• When testing in Firefox, make sure you open the page with HTTPS
• Put joomla in debug mode
• In the debug plugin with make sure that the Profile collector is enabled (is by default)
• Open any page
• Open the dev tools and check the Network tab
• Select the first entry and then click on the timings tab of the specific request

Actual result BEFORE applying this Pull Request

Only the request timing information is shown.

Expected result AFTER applying this Pull Request

Beside the request timing is the server timing information shown.

[dgrammatiko]

I have tested this item ✅ successfully on cf42d70

@bembelimen this would be great Dev DX if could land in 4.1

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/36231.}

[Quy]

Maybe add a colon after each description for consistency.

[laoneo]

@Quy that's how it comes from the profiler. How would you do it then, can you make a suggestion?

[Quy]

I have tested this item ✅ successfully on 27300cf

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/36231.}

[Quy]

RTC

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/36231.}

[bembelimen]

Thx