Better interpolation

[percevalw]

Description

• Support interpolated seed in the config file (as a reminder, the seed is treated specifically by confit to initialize random generators before any object is resolved)
• Support if/else expressions in interpolation, and only resolve the relevant branch

Checklist

• If this PR is a bug fix, the bug is documented in the test suite.
• Changes were documented in the changelog (pending section).
• If necessary, changes were made to the documentation.

[github-actions]

Coverage Report

Name	Stmts	Miss	∆ Miss	Cover
TOTAL	955	18	0	98.12%

Files without new missing coverage

Name	Stmts	Miss	∆ Miss	Cover
confit/utils/settings.py Was already missing at lines 10-12 return bool(loads(value)) - except Exception: - return True	10	2	0	80.00%
confit/registry.py Was already missing at line 119 if name is None and hasattr(e.model, "type_"): - name = e.model.type_.__module__ + "." + e.model.type_.__qualname__ e = ConfitValidationError( Was already missing at lines 479-484 """ - entrypoints = importlib_metadata.entry_points() ... - return entrypoints.get(self.entry_point_namespace, []) Was already missing at line 509 if from_entry_point: - return from_entry_point if not catalogue.check_exists(*path): Was already missing at line 516 ) - return catalogue._get(path)	214	7	0	96.73%
confit/config.py Was already missing at line 126 else: - current = current[part] try: Was already missing at line 153 if resolve: - return config.resolve(registry=registry) Was already missing at line 375 return local_names[parts] + ("." if path.endswith(":") else "") - except KeyError: raise KeyError(path) Was already missing at line 420 if not deep and len(loc) > 1: - return obj Was already missing at line 500 return - current[path] = val Was already missing at line 527 ): - old[key] = new_val else: Was already missing at line 563 elif isinstance(obj, list): - return [rec(v) for v in obj] elif isinstance(obj, tuple): Was already missing at line 565 elif isinstance(obj, tuple): - return tuple(rec(v) for v in obj) elif isinstance(obj, Reference): Was already missing at line 614 if isinstance(config_paths, Path): - config_paths = [config_paths]	304	9	0	97.04%

8 files skipped due to complete coverage.

Coverage success: total of 98.12% is above 98.08% 🎉