[FIX] web: form's title should take all width in edit mode

Form sheet's title (with class .oe_title) when in editable mode has a
maximum width. The goal according to FP is to make a clear
differentiation between the main title/name of a record and its other
fields.

An issue with the existing rule in the Project application is that the
"title" row (with class .oe_title) not only contains the name of the
task but also its priority and state.

The aforementioned rule should then be applied only on the "name" part
and not to the whole row to prevent the "state" from moving between
read_only and editable modes.

To do so the maximum width is "moved" from the row element to the task
name's element.

Sadly the current stylesheet in this project is still a regular CSS
file, preventing us from using the SCSS expression coming from
`addons/web/static/src/scss/form_view.scss`.

Task ID: 1946570

closes odoo/odoo#33845

Signed-off-by: Adrien Dieudonné (adr) <adr@odoo.com>

addons/project/static/src/css/project.css

@@ -38,3 +38,16 @@
   margin-top: 6px;
   margin-right: 8px;
 }
+
+.o_form_project_tasks.o_form_editable .oe_title {
+  max-width: initial;
+}
+
+.o_form_project_tasks.o_form_editable .oe_title .o_task_name {
+  /*
+   * should be (coming from addons/web/static/src/scss/form_view.scss):
+   * max-width: map-get($container-max-widths, md) - (2 * $o-horizontal-padding);
+   */
+  max-width: 688px;
+  margin-right: auto;
+}