Improve exception messages

[mnapoli]

Improve exception messages: simpler and more consistent. Added more tests too.

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Before

Entry DI\Test\IntegrationTest\ErrorMessages\Buggy1 cannot be resolved: The parameter 'bar' of DI\Test\IntegrationTest\ErrorMessages\Buggy1::__construct has no value defined or guessable
Object (
    class = DI\Test\IntegrationTest\ErrorMessages\Buggy1
    scope = singleton
    lazy = false
    __construct(
        $foo = 'some value'
        $bar = #UNDEFINED#
        $default = (default value) 123
    )
)

After

Entry "DI\Test\IntegrationTest\ErrorMessages\Buggy1" cannot be resolved: Parameter $bar of __construct() has no value defined or guessable
Object (
    class = DI\Test\IntegrationTest\ErrorMessages\Buggy1
    scope = singleton
    lazy = false
    __construct(
        $foo = 'some value'
        $bar = #UNDEFINED#
        $default = (default value) 123
    )
)

---

Before

Entry DI\Test\IntegrationTest\ErrorMessages\InterfaceFixture cannot be resolved: class DI\Test\IntegrationTest\ErrorMessages\InterfaceFixture is not instantiable
Full definition:
Object (
    class = #NOT INSTANTIABLE# DI\Test\IntegrationTest\ErrorMessages\InterfaceFixture
    scope = singleton
    lazy = false
)

After

Entry "DI\Test\IntegrationTest\ErrorMessages\InterfaceFixture" cannot be resolved: the class is not instantiable
Full definition:
Object (
    class = #NOT INSTANTIABLE# DI\Test\IntegrationTest\ErrorMessages\InterfaceFixture
    scope = singleton
    lazy = false
)

---

Before

The factory definition "Acme\UserRepository" is not callable: RepositoryFactory is neither a callable or a valid container entry

After

Entry "Acme\UserRepository" cannot be resolved: factory "RepositoryFactory" is neither a callable nor a valid container entry