[14.0][ADD] New module: account_move_line_merge_split

[carlossainznetkia]

Ref: #728 (comment)

This module provides functionality to split and merge accounting move lines in Odoo.
Features

Split Move Lines
    Users can divide a single accounting move line into multiple lines.
    The wizard allows specifying the number of divisions and automatically calculates the amounts and due dates for the new lines.
    Validation ensures the original move line has a maturity date and prevents splitting reconciled entries.

Merge Move Lines
    Users can merge multiple move lines into a single line.
    The wizard checks that all selected move lines belong to the same journal entry and account.
    The resulting move line consolidates the debit and credit values while preserving the aggregation date.

Usage

Splitting Move Lines
    Select a single move line in the list view.
    Click on the "Action" button and select "Split Move Lines".
    Specify the number of divisions in the wizard and confirm.

Merging Move Lines
    Select multiple move lines in the list view.
    Click on the "Action" button and select "Merge Move Lines".
    Confirm in the wizard to generate the merged move line.