Feature: #83835 - Check more fields in Link Validator 

Description 

Some additional fields were added to Page TSconfig mod.linkvalidator.searchFields:

• pages = canonical_link
• sys_redirect = target
• sys_file_reference = link

Two special fields are currently defined, but are not checked yet due to their TCA configuration. For forward compatibility, these are kept in the field configuration:

• pages = media has TCA type="file"
• tt_content = records has TCA type="group"

The following fields could theoretically be included in custom configurations, as their type / softref is available, but they are specifically not added in the default configuration:

• sys_webhook = url (webhook should not be invoked)
• tt_content = subheader (has softref email[subst] which is not a supported link type)
• pages = tsconfig_includes (system configuration)
• sys_template = constants, include_static_file, config (system configuration)
• tx_scheduler_task_group = groupName (scheduler system configuration)

Impact 

Broken links in sys_file_reference.link, sys_redirect.target and pages.canonical_link will now be checked.

Any enabled field will only be checked, if there is TCA configured, so for example pages.canonical_link will only be checked if EXT:seo is installed.