[ReaAct] Lock via automatic JOIN queries

• Specifying a dictionary of requested models and some of its fields and relations should automatically create a JOIN query.
• This should also specify if the models should be locked for update, having the advantage that models/rows are locked at once.
• filter data structure or client autoupdate subscription data structure might be an inspiration on how to do it

Example from BaseMigration:

join_on_parts: list[sql.Composable] = []
for table, join_on_columns in additional_source_tables.items():
    join_on_parts.append(
        get_join_table_part(table, join_on_columns)
    )
    join_on = sql.SQL(" ").join(join_on_parts)

def get_join_table_part(
right_table: Table, join_on_columns: dict[Field, tuple[Table, Field]]
) -> sql.Composable:
    return sql.SQL(" JOIN {right_table} ON {columns}").format(
        right_table=sql.Identifier(right_table),
        columns=sql.SQL(" AND ").join(
        sql.SQL(
           "{right_table}.{right_column} = {left_table}.{left_column}"
        ).format(
            right_table=sql.Identifier(right_table),
            right_column=sql.Identifier(right_column),
            left_table=sql.Identifier(left_table_and_column[0]),
            left_column=sql.Identifier(left_table_and_column[1]),
        )
        for right_column, left_table_and_column in join_on_columns.items()
    ),
)

Example of additional_source_tables:

main_source_table = "vote_t"
additional_source_tables={
    "meeting_user_t": {
        "user_id": ("vote_t", "user_id"),
        "meeting_id": ("vote_t", "meeting_id"),
    },
    "option_t": {"id": ("vote_t", "option_id")},
    "poll_t": {"id": ("option_t", "poll_id")}
}

Start by reading the BaseMigration JOIN example and compare it with the filter data structure and client autoupdate subscription data structure mentioned in the issue. Define how requested models, fields, relations, and update locking should be represented, then verify that the resulting query joins the required tables and locks the requested rows together.