Remove WriteContext from public API

[JoerivanEngelen]

Somewhere around 5523c24 the WriteContext was introduced, this is an object to collect settings for writing (directory, save as binary, etc.). This is generated internally when calling Modflow6Simulation.write. The WriteContext is passed through from Simulation to Model to Package, and accepted as argument for the Package.write class. However, this altered the public API, as now users have to first create a WriteContext, an object stowed away in a non-public module, to be able to write their packages separately.

I'm not sure how large the use-case is, but it the write context is quite an extra hurdle for users now to call a method that is part of the public API. I like the idea of the context, so to work around this, we could make the current write a semi-private _write, and create a separate method for the public API which collects all settings and calls _write. Modflow6Simulation.write would then directly call _write.

The only downside of this is that extending the WriteContext with some extra settings, might require some extra work, as arguments have to be added as well. However, I think that is worth it now, as letting users create internal objects to do what they want to do is also unwanted.

Something like:

class Package:
...

    def write(
        self,
        pkgname: str,
        globaltimes: Union[list[np.datetime64], np.ndarray],
        directory: str,
        binary: bool = True,
        use_absolute_paths = False,
    ):
       write_context = WriteContext(directory, binary, use_absolute_paths)
       self._write(pkgname, globaltimes, write_context)

    @standard_log_decorator()
    def _write(
        self,
        pkgname: str,
        globaltimes: Union[list[np.datetime64], np.ndarray],
        write_context: WriteContext,
    ):
        directory = write_context.write_directory
        binary = write_context.use_binary
        self.write_blockfile(pkgname, globaltimes, write_context)

        if hasattr(self, "_grid_data"):
            if self._is_xy_data(self.dataset):
                pkgdirectory = directory / pkgname
                pkgdirectory.mkdir(exist_ok=True, parents=True)
                for varname, dtype in self._grid_data.items():
                    key = self._keyword_map.get(varname, varname)
                    da = self.dataset[varname]
                    if self._is_xy_data(da):
                        if binary:
                            path = pkgdirectory / f"{key}.bin"
                            self.write_binary_griddata(path, da, dtype)
                        else:
                            path = pkgdirectory / f"{key}.dat"
                            self.write_text_griddata(path, da, dtype)