Dayjs locales are very limited compared to MomentJS

**Describe the bug**
Not a bug but a feature request. The day.js locales only have a small subset of the data compared to MomentJS. This can result in unexpected behaviour when migrating from MomentJS to day.js.

For example, consider the `de` translations for [day.js](https://github.com/iamkun/dayjs/blob/dev/src/locale/de.js) and [MomentJS](https://github.com/moment/moment/blob/develop/src/locale/de.js). MomentJS has calendar values. This makes it possible to output things like "Tomorrow at 12:30pm".

**Expected behavior**
Day.js should provide the same locale data as MomentJS.

**Information**
- Day.js Version: 1.8.36
- OS: MacOS Catalina
- Browser: FireFox
- Time zone: EST

Start by comparing src/locale/de.js with the linked MomentJS de.js locale file, focusing on missing calendar values and other locale data. Determine whether the expected parity applies to German only or to all Day.js locales; done means the requested locale data is available and the migration behavior matches the corresponding MomentJS data.

Written by the indexing model from the issue text.