Allow adding created group with dynamic roles to an XWiki object field

When automatically creating groups with the dynamic roles feature, it is sometimes desirable to keep tabs on them and add these groups to some fields.

For instance, for `XWiki.Prj_` groups dynamically created from  project_ roles, we may want to add them in an ldap_group_mapping field in XWiki Preferences like this:

XWiki.Prj_1=cn=project_1,ou=users,dc=xwiki,dc=com|XWiki.Prj_2=cn=project_2,ou=users,dc=xwiki,dc=com|XWiki.Prj_3=cn=project_3,ou=users,dc=xwiki,dc=com|XWiki.EmployeeType_other=cn=employeetype_other,ou=users,dc=xwiki,dc=com|XWiki.EmployeeType_other=cn=employeetype_XXX,ou=users,dc=xwiki,dc=com|XWiki.EmployeeType_XXX=cn=employeetype_XXX,ou=users,dc=xwiki,dc=com{}

Given a configuration like:

xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.page=XWiki.XWikiPreferences
xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.className=XWiki.XWikiPreferences
xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.objectNumber=0
xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.propertyName=ldap_group_mapping
xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.separator=|
xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.valueRegex=^(?<group>[^=]+)=
xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.value={group}=cn={role},ou=users,dc=xwiki,dc=com{}

The above could be achieved with a configuration like this:

xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.page=XWiki.XWikiPreferences
xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.className=XWiki.XWikiPreferences
xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.objectNumber=0
xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.propertyName=ldap_group_mapping
xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.separator=|
xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.valueRegex=^(?<group>[^=])=.
xwiki.authentication.trusted.dynamicRole.configuration.project.addGroupToField.value={group.fullName}=cn={role},ou=users,dc=xwiki,dc=com

Description of each configuration fields to add:

addGroupToField.page = The document in which to add the value

addGroupToField.className (optional) = The class name of the object to use. If not given, the first object with the given property name will be used.

addGroupToField.objectNumber (optional) = The object number to use. If not specified, the first object of the given class name will be used.

addGroupToField.propertyName  = The name of the property (field) to use.

addGroupToField.separator (optional) = The string that separates the values in this field. By default, a pipe character (|)

addGroupToField.valueRegex (optional) = The regex that will be used to match values. If there is a group named capture group is used, the matched part will be compared to / matched with the group being added. If there is a role named capture group is used, the role will be matched. By default, ^(?<group>[^=]+)=[\s\S]* is used. This means that values beginning with the name of the group being created, immediately followed by an equal sign, will be matched.

addGroupToField.valueFormat(optional) = the format of the value to add. {{

{group.fullName}}} is replaced with the full group name (e.g. XWiki.Project_1) without the wiki part, {group.name} is replaced with the base name (e.g. Project_1), {group} is replaced with the full reference including the wiki name (e.g. xwiki:XWiki.Project_1), {role} is replaced with the role. The backslash is an escape character which can be escaped with itself. By default, {{{group.fullName}

={role}}} is used.

A configuration common to all dynamic role configurations can be used: xwiki.authentication.trusted.dynamicRole.addGroupToField. Specific configurations will override this one.