Fix harmmean Inf vecdim validation

[sahilphad07-sudo]

harmmean accepted Inf values in the vecdim argument and silently ignored them. MATLAB rejects non-finite dimension values with an error.

This change updates vecdim validation to reject non-finite values, matching MATLAB behavior.

Before

octave:1> harmmean ([1 2 4], [1 Inf])
ans =

   1   2   4

After

octave:1> harmmean ([1 2 4], [1 Inf])
error: harmmean: DIM must be a positive integer scalar or vector.

The same validation now applies to all occurrences of Inf in vecdim.

MATLAB Behavior

>> harmmean([1 2 4], [1 Inf])
Error using sum
Dimension argument must be a positive integer scalar, a vector of unique positive integers, or 'all'.

Regression Tests Added

• Scalar Inf dimension
• Inf after a valid dimension: [1 Inf]
• Inf before a valid dimension: [Inf 1]
• Multiple Inf dimensions: [Inf Inf]

Test Results

All existing and new harmmean BISTs pass:

PASSES 27 out of 27 tests.