Tests for Instrumental Variable Validity // Implements tests for the identifying assumptions of instrumental variable models, the local exclusion restriction and monotonicity conditions required for local average treatment effect identification. Covers Kitagawa (2015) doi:10.3982/ECTA11974, Mourifie and Wan (2017) doi:10.1162/REST_a_00622, and Frandsen, Lefgren, and Leslie (2023) doi:10.1257/aer.20201860. Includes a one-shot wrapper that runs all applicable tests on a fitted instrumental variable model. Dispatches on 'fixest' and 'ivreg' model objects.