feat(QDate): support different date formats when using events (#16735)

[IceIsFrozen]

What kind of change does this PR introduce?

• Bugfix
• Feature
• Documentation
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change?

• Yes
• No

The PR fulfills these requirements:

• It's submitted to the dev branch (or v[X] branch)
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix: #xxx[,#xxx], where "xxx" is the issue number)
• It's been tested on a Cordova (iOS, Android) app
• It's been tested on an Electron app
• Any necessary documentation has been added or updated in the docs or explained in the PR's description.

Other information:

Adds support for dashes(ISO 8601) and dots by normalizing them into quasar's desired slash date format. Everything should probably normalize into ISO 8601 format in the future but this works fine.

2019/02/01 - Originally supported
2019-02-01 - Support added
2019.02.01 - Support added