Improve date parsing in StringUtils and make DelayInformationProvider use StringUtils for date parsing.
Description
Move the parsing code in the current provider into StringUtils so it can use a common parsing utility. Make StringUtils parse XEP-0082 and XEP-0091 formats.
Move the parsing code in the current provider into StringUtils so it can use a common parsing utility.
Make StringUtils parse XEP-0082 and XEP-0091 formats.