[flang] Implemented a warning about contiguity of compile time constant values (#161084)

Implemented `common::UsageWarning::ConstantIsContiguous` to warn about
the
following case:
```
integer, parameter :: num = 3
integer, parameter :: arr(num)=[(i, i=1,num)]
logical, parameter :: result=is_contiguous(arr(num:1:-1))
end
```
Here, while array section is discontiguous, `arr` is a compile time
constant,
so array section created at compile time will end up being contiguous
and
`result` will be "true". If `arr` wasn't a constant, the result at
runtime
would have been "false".

0 files changed, 0 insertions, 0 deletions