[Chat UI] message input "date" should allow for different date formatting

Issue type

I’m submitting a … (check one with “x”)

• bug report
• feature request

Issue description

Current behavior:

I saw in https://github.com/akveo/nebular/blob/master/src/framework/theme/components/chat/chat-message-text.component.ts#L15 that the date input into nb-chat-message is always piped into shortTime. This is confusing if the messages span multiple days. Can something like datePipeFormat: string (https://angular.io/api/common/DatePipe#pre-defined-format-options) be added as an input as well?

Expected behavior:

The chat messages would display the date as well to prevent confusing over messages spanning multiple days.

Steps to reproduce:

Add messages to nb-chat-message where the dates span multiple days.

Other information:

npm, node, OS, Browser

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Node, npm: `node --version` and `npm --version`
OS: Windows (7/8/10). Linux (incl. distribution). macOS (El Capitan? Sierra?)
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node --version
v10.16.0

npm --version
6.9.0

OS: macOS Mojave
Browser: Chrome

[erickconcepcion]

I want it too.

[piotrbrzuska]

sounds like done. this issue should be closed