Add RenderNameCase.LOWER_IF_UNQUOTED and UPPER_IF_UNQUOTED

[lukaseder]

In #5909, we've cleanly separated the two features:

• Quoting of names
• Upper / lower casing of names

No new features were introduced, just the separation was implemented. However, the behaviour of RenderNameCase.LOWER and UPPER is not so terribly useful when we specify RenderQuotedNames.ALWAYS, as it might lead to wrong SQL (such as referencing "INFORMATION_SCHEMA" on PostgreSQL, or "information_schema" on H2).

This is why we need additional LOWER_IF_UNQUOTED and UPPER_IF_UNQUOTED flags in RenderNameCase, which modify names only if they're not quoted. (i.e. DSL.unquotedName()). The following test shows the expected behaviour:

    @Test
    public void testRenderNameCaseOfQuotedAndUnquotedNames() {
        Name name = name(quotedName("Quoted"), unquotedName("Unquoted"));

        assertEquals("`Quoted`.Unquoted", r_ref().render(name));

        create.settings().setRenderNameCase(RenderNameCase.LOWER);
        assertEquals("`quoted`.unquoted", r_ref().render(name));

        create.settings().setRenderNameCase(RenderNameCase.LOWER_IF_UNQUOTED);
        assertEquals("`Quoted`.unquoted", r_ref().render(name));

        create.settings().setRenderNameCase(RenderNameCase.UPPER);
        assertEquals("`QUOTED`.UNQUOTED", r_ref().render(name));

        create.settings().setRenderNameCase(RenderNameCase.UPPER_IF_UNQUOTED);
        assertEquals("`Quoted`.UNQUOTED", r_ref().render(name));
    }