tests: interrupt: add testcase for functions in the sw_isr_table

Validate the following functions in the sw_isr_table:
- z_get_sw_isr_table_idx
- z_get_sw_isr_device_from_irq
- z_get_sw_isr_irq_from_device

Signed-off-by: Yong Cong Sin <ycsin@meta.com>