Fix bug: Missing to load the "net/http" library. (#12506)

transitive dependency was removed from firefox driver file without replacing net/http requirement, preventing http calls for Firefox driver without the user first requiring the library.
this moves the requirement to webdriver file instead of putting it in each driver file

Author: dvarrui

rb/lib/selenium/webdriver.rb

@@ -23,6 +23,7 @@
 require 'json'
 require 'set'
 require 'uri'
+require 'net/http'
 
 require 'selenium/webdriver/atoms'
 require 'selenium/webdriver/common'

rb/lib/selenium/webdriver/chrome.rb

@@ -17,8 +17,6 @@
 # specific language governing permissions and limitations
 # under the License.
 
-require 'net/http'
-
 module Selenium
   module WebDriver
     module Chrome

rb/lib/selenium/webdriver/chromium.rb

@@ -17,8 +17,6 @@
 # specific language governing permissions and limitations
 # under the License.
 
-require 'net/http'
-
 module Selenium
   module WebDriver
     module Chromium

rb/lib/selenium/webdriver/edge.rb

@@ -17,8 +17,6 @@
 # specific language governing permissions and limitations
 # under the License.
 
-require 'net/http'
-
 module Selenium
   module WebDriver
     module Edge