[10.x] Set application_name and character set as PostgreSQL DSN string

[sunaoka]

This pull request resolves the following

The following queries are executed when you set the character set and application name in PostgreSQL, respectively.

Set name to 'charset'

set application name to 'Application Name'

However, PostgreSQL allows you to set each in a DSN string.

pgsql:host=foo;dbname='bar';client_encoding='utf8';application_name='Laravel App'

This prevents the above two queries from being executed every time another query is executed.