Add helper functions from `DataFrame` to `LogicalPlanBuilder`

[abhiaagarwal]

Is your feature request related to a problem or challenge?

I'm trying to remove some explicit DataFrame references in delta-rs' codebase to operate directly on Logical Plans instead, so we can stream and materialize later in the process. Most methods on DataFrame are a wrapper around LogicalPlanBuilder, except for the with_columnfunction.

Describe the solution you'd like

I propose that we add a new trait, LogicalPlanBuilderExt, that adds convenience methods with_column (and select, etc) that performs the exact operations that DataFrame is using.

datafusion/datafusion/core/src/dataframe/mod.rs

Lines 2135 to 2187 in d13d891

	pub fn with_column(self, name: &str, expr: Expr) -> Result<DataFrame> {
	let window_func_exprs = find_window_exprs([&expr]);
	let original_names: HashSet<String> = self
	.plan
	.schema()
	.iter()
	.map(|(_, f)| f.name().clone())
	.collect();
	// Maybe build window plan
	let plan = if window_func_exprs.is_empty() {
	self.plan
	} else {
	LogicalPlanBuilder::window_plan(self.plan, window_func_exprs)?
	};
	let new_column = expr.alias(name);
	let mut col_exists = false;
	let mut fields: Vec<(Expr, bool)> = plan
	.schema()
	.iter()
	.filter_map(|(qualifier, field)| {
	// Skip new fields introduced by window_plan
	if !original_names.contains(field.name()) {
	return None;
	}
	if field.name() == name {
	col_exists = true;
	Some((new_column.clone(), true))
	} else {
	let e = col(Column::from((qualifier, field)));
	Some((e, self.projection_requires_validation))
	}
	})
	.collect();
	if !col_exists {
	fields.push((new_column, true));
	}
	let project_plan = LogicalPlanBuilder::from(plan)
	.project_with_validation(fields)?
	.build()?;
	Ok(DataFrame {
	session_state: self.session_state,
	plan: project_plan,
	projection_requires_validation: false,
	})
	}

This also helps DataFrame become a loose wrapper around LogicalPlanBuilder and lets the logic live in datafusion_expr.

Describe alternatives you've considered

N/A

Additional context

N/A