MDEV-30931 UBSAN: negation of -X cannot be represented in type 'long long int'; cast to an unsigned type to negate this value to itself in get_interval_value on SELECT

- Fixing the code in get_interval_value() to use Longlong_hybrid_null.
  This allows to handle correctly:

  - Signed and unsigned arguments
    (the old code assumed the argument to be signed)
  - Avoid undefined negation behavior the corner case with LONGLONG_MIN

  This fixes the UBSAN warning:
    negation of -9223372036854775808 cannot be represented
    in type 'long long int';

- Fixing the code in get_interval_value() to avoid overflow in
  the INTERVAL_QUARTER and INTERVAL_WEEK branches.
  This fixes the UBSAN warning:
    signed integer overflow: -9223372036854775808 * 7 cannot be represented
    in type 'long long int'

- Fixing the INTERVAL_WEEK branch in date_add_interval() to handle
  huge numbers correctly. Before the change, huge positive numeber
  were treated as their negative complements.
  Note, some other branches still can be affected by this problem
  and should also be fixed eventually.