Provide OID domains per layers

[signedav]

This PR provides the OID domain (type) over the Layer object.

This is the approach the Plugin using the Generator and not calling a db_connector function directly. The reason is, to have the information about the relevance of a layer, alias (that will be used in the project later) etc. and we can set the default_expression directly.

How I imagine it to work:

It's reloaded on changing the strategy - and the generator is persisted for further project generation:

0. getting the Generator

generator = Generator(
    self.configuration.tool,
    uri,
    self.configuration.inheritance,
    self.configuration.dbschema,
    mgmt_uri=mgmt_uri,
    consider_basket_handling=True,
    optimize_strategy=self.optimize_combo.currentData(),
)

and on changing the strategy in the GUI:

generator.optimize_strategy = self.optimize_combo.currentData()

and getting the list of layers...

1. getting a list of the layers visible in the project (according to relevance and strategy) not concerning the system tables

available_layers = generator.layers()
# maybe make it more readable and less single linish
layers_of_interest = [
    l for l in available_layers if (l.is_relevant or self.optimize_combo.currentData() != optimize_strategy.HIDE) and l.name not in self.BASKET_TABLES
]

2. Getting the oid type (and the other info)

for layer in layers_of_interest:
      oid_entry['oid_domain']=layer.oid_domain

3. Set the default_expressions

layer.t_ili_tid_field.default_value_expression = "'ch_baker'||ilicounter(000000000,999999999)"

Limitations

If a CLASS is designed in a TOPIC (with ANYOID) and it's extended in multiple other TOPICS with different OID definitions, we cannot say what should be the default value. This is a known limitation or maybe we find a solution for it.

[signedav]

The changes on the class are not that big, in fact only a nice provide of the oid_domain (the type) and the t_ili_tid field (oid field). Then some tests and in the end kind of a proof of concept...

[domi4484]

Suggested change

	t_ili_tid_field = self.t_ili_tid_field
	t_ili_tid_field = self.t_ili_tid_field()

Missing parentheses?

[domi4484]

Ah no its a property...

[signedav]

Thanks @domi4484 I think here you would have already the basics for the GUI implementation. Maybe you will find some more requirements to it during implementation. I'll make a release of the library.