Validate duration literals

[barmac]

Problem you would like to solve

It is absolutely frustrating when you get a runtime error for incorrect duration value, e.g. duration("PTS15"). One needs to be an ISO8601 expert to spot the problem here.

Proposed solution

Validate this! We can easily validate the duration("...") string literal part with a regex. We already do that in in dmn-js, so why don't we do that everywhere? This should be implemented at feel-lint level as it supports any FEEL editor user.

This will support "Editors, not drawing writing tools".

Alternatives considered

Do nothing and let the users suffer.

Additional context

This conversation: https://camunda.slack.com/archives/C057H178R9T/p1737455728395989

[nikku]

If tackled this should be fixed in feel-lint, where we already host another rule: https://github.com/bpmn-io/feel-lint/blob/main/rules/first-item.js.

Should not only be solved for string input to date, date and time and time fields, but also for AtLiterals, the modern way to create date and time values: `@"2019-03-31".