Feature: #86918 - Add additional configuration for external link types in Linkvalidator

Description

Additional configuration is added for crawling external links:

mod.linkvalidator {

    linktypesConfig {
       external {

          # User-Agent string is filled with information about the crawling site
          httpAgentName = TYPO3 Linkvalidator
          httpAgentUrl =
          httpAgentEmail =

          headers {
          }

          method = HEAD

          range = 0-4048
       }
    }

For a description of the fields, see the linkvalidator documentation: https://docs.typo3.org/c/typo3/cms-linkvalidator/main/en-us//Configuration/Index.html

It is recommended to fill out httpAgentUrl and httpAgentEmail so that the User-Agent string is filled for crawling external URLs.

For headers, method and range it is recommended to stick with the default values.

Impact

It is possible to configure information for the 'User-Agent' string as is customary for crawlers.

The settings 'headers', 'method' and 'range' are advanced settings. They can be used to optimize the crawling.

Recommendation

Set the settings httpAgentUrl and httpAgentEmail. Details can be found in the linkvalidator documentation.