add utility classes for dca sorting modes and flags

[Tastaturberuf]

add readable sorting modes and flags for using in the dca files

[qzminski]

That's a good idea but I think this should rather be a Contao core code. @Toflar @aschempp

[Tastaturberuf]

I think the same but i want to have it asap and in older contao versions like 3.5 LTS and 4.4 LTS. That's why this is also a 'haste' feature.

[aschempp]

I like the idea and I'm fine with adding it to Haste. But I think the constant names should be shorter and the classes should be in Haste\Dca namespace.

[qzminski]

I agree with moving it to the Dca namespace. Also, the names could be shortened a bit:

NOT_SORTED => NONE
SORTED_FIXED_FIELD => FIXED_FIELD
SORTED_SWITCHABLE_FIELD => SWITCHABLE_FIELD
SORTED_PARENT_TABLE => PARENT_TABLE
DISPLAY_AS_CHILD => CHILD_VIEW
DISPLAY_AS_TREE => TREE_VIEW
DISPLAY_AS_CHILD_TREE => CHILD_TREE_VIEW

[Tastaturberuf]

Thanks for the feedback. I update the PR

[qzminski]

Thanks @Tastaturberuf !

[qzminski]

I have just released 4.19.0.