[3.x] Fix refresh() on EmbedsOne

[fix] Make newPivotQuery function public

Laravel versions starting from 6 are all  6.x

PR https://github.com/laravel/framework/pull/31677 made newPivotQuery function public and that's the reason why builds are failing.

Fix getDefaultDatabaseName to handle +srv URLs.

Fixes #1977, fixes #1861

Fix a typo

`belongsToMany` operation is imporing the `Model` with a typo. Fixed it.

[refactor] tests

[fix] default database detection from dsn

Refactored default database function which detects based on db config or tries to detect it from dsn

Add MIT license

There is no currently license file, PR https://github.com/jenssegers/laravel-mongodb/pull/1780 was pushed to develop branch.

[fix] Correct import class for DB in Queue

PR https://github.com/jenssegers/laravel-mongodb/pull/1851 had incorrect class import, we need to define correct path, see issue https://github.com/jenssegers/laravel-mongodb/issues/1868

[Fix] Format exception to string in failed jobs

[Updated PR#1534] UTCDateTime conversion now includes milliseconds

[Updated PR#1745] Bugfix create collection with options

Add getCollection function and little improvements

[Updated PR#1378] Fix Carbon import on Model as Laravel

Format exception to string so it can be saved correctly. See https://github.com/laravel/framework/blob/6.x/src/Illuminate/Queue/Failed/DatabaseFailedJobProvider.php#L59

[Updated PR#1145] Fix paginate in EmbedsMany