[IMP] web: add nolabel to list view

This commit adds the support of nolabel attribute on fields
in list view. This attribute can be used to empty the column header.

Example of use:

<record id="module_example_tree_view" model="ir.ui.view">
  <field name="name">module.example.tree.opportunity</field>
  <field name="model">module.example</field>
  <field name="arch" type="xml">
    <tree>
      <field name="name"/>
      <field name="tag_ids" widget="many2many_tags" nolabel="1"/>
    </tree>
  </field>
</record>

Result:

This will create a tree view with 2 columns.
The second column will have an empty header and won't be sortable.

Name    |
--------+--------------
Record1 | [tag1]
Record2 | [tag1][tag2]
Record3 | [tag2]

closes odoo/odoo#52302

Task: 2269315
Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>