feature(config): implement global module config via forRoot

[smhagit]

currently only the [messages] are supported

Change-Id: I772a95861ffa36353430123526a9f9e82fa0187e

What kind of change does this PR introduce? (check one with "x")

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior? (You can also link to an open issue here)
Currently the localization for the [messages] must be set in html for every ngx-datatable instance.
An already existing Issue from @fantoine last year=> #1602

What is the new behavior?
With this change, you can set the [messages] globally via Module.forRoot

// Import the Module with forRoot
NgxDatatableModule.forRoot({
      messages: {
        emptyMessage: 'No data to display',   // Message to show when array is presented, but contains no values
        totalMessage: 'total',                // Footer total message
        selectedMessage: 'selected'           // Footer selected message
      }
    })

Does this PR introduce a breaking change? (check one with "x")

• Yes
• No

If this PR contains a breaking change, please describe the impact and migration path for existing applications: ...

Other information:

[marjan-georgiev]

Nice feature, thanks! Will be released in 15.1.0

[conrado-l]

I think it would be a great idea to be able to set the cssClasses too, such as the pagination and sorting icons via forRoot, repeating the cssClasses input in every is pretty bad.

¡Thanks!

[hensleyrob]

Nice feature, thanks! Will be released in 15.1.0

I could use this as well, any timeline on the 15.1.0 release?