Error on calling polars.Expr.meta.tree_format with expressions from list of columns

[Aamlsmfc]

Checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of Polars.

Reproducible example

import polars
polars.col("a", "b").meta.tree_format()

Log output

thread 'ipython' panicked at crates/polars-plan/src/logical_plan/conversion.rs:160:33:
no `columns` expected at this point
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
---------------------------------------------------------------------------
PanicException                            Traceback (most recent call last)
<ipython-input-2-71d2003df3e0> in <module>
----> 1 polars.col("a", "b").meta.tree_format()

../lib/python3.8/site-packages/polars/_utils/deprecation.py in wrapper(*args, **kwargs)
    224             if len(args) > num_allowed_args:
    225                 issue_deprecation_warning(msg, version=version)
--> 226             return function(*args, **kwargs)
    227
    228         wrapper.__signature__ = new_sig  # type: ignore[attr-defined]

../lib/python3.8/site-packages/polars/expr/meta.py in tree_format(self, return_as_string)
    308         >>> e.meta.tree_format(return_as_string=True)  # doctest: +SKIP
    309         """
--> 310         s = self._pyexpr.meta_tree_format()
    311         if return_as_string:
    312             return s

PanicException: no `columns` expected at this point

Issue description

The polars.expr.meta interface does not fully support expressions for functions taking as input multiple columns. Thus, using meta functions on expression such as polars.col(["a", "b"]).some_function() often throws errors.

Here is a small example that throws an error.

Expected behavior

One would have expected an output like the one below:

        0
   ┌─────────────────────
   │
   │  ╭──────────────╮
 0 │  │ cols([a, b]) │
   │  ╰──────────────╯

Installed versions

--------Version info---------
Polars:               0.20.16
Index type:           UInt32
Platform:             Linux-3.10.0-1160.el7.x86_64-x86_64-with-glibc2.2.5
Python:               3.8.16 (default, Apr 26 2023, 19:39:47)
[GCC 9.3.1 20200408 (Red Hat 9.3.1-2)]

----Optional dependencies----
adbc_driver_manager:  <not installed>
cloudpickle:          <not installed>
connectorx:           0.3.2
deltalake:            <not installed>
fastexcel:            <not installed>
fsspec:               <not installed>
gevent:               <not installed>
hvplot:               0.9.2
matplotlib:           3.7.1
numpy:                1.23.5
openpyxl:             <not installed>
pandas:               1.5.3
pyarrow:              15.0.0
pydantic:             <not installed>
pyiceberg:            <not installed>
pyxlsb:               <not installed>
sqlalchemy:           1.4.46
xlsx2csv:             <not installed>
xlsxwriter:           3.1.2