This commit adds optimised l32i/s32i functions that select the best load/
store encoding based on the size of the offset, and uses the function when
necessary in code generation.
Without this, ASM_LOAD_REG_REG_OFFSET() could overflow the word offset
(using a narrow encoding), for example when loading the prelude from the
constant table when there are many (>16) constants.
Fixes issue #8458.
Signed-off-by: Damien George <damien@micropython.org>
