This PR adds support to be able to generate `acc.bounds` operation
through `MappableType`'s `generateAccBounds` when there is no fir.box
entity. This is especially useful because the FIR type does not capture
size information for explicit-shape arrays and current implementation
relied on finding the box entity.
This scenario is possible because during HLFIRtoFIR, `fir.array_coor`
and `fir.box_addr` operations are often optimized to use raw address. If
one tries to map the ssa value that represents such a variable, correct
dimensions need extracted from the shape information held in the fir
declare operation.
b20e063a90