stdlib_io: add print_array function to print arrays to output units

[zoziha]

Description

Add print_array subroutine, which is used to print two-dimensional arrays of integer and floating-point types. These two types are more commonly used in Fortran. It supports arguments such as delimiter, output unit, output format, and whether to print briefly.

In the non-brief output mode, the print_array function can produce an output result style similar to that of savetxt in stdlib_io. The print_array function is mainly convenient for users to output to the screen (standard output) and is likely to be mostly used for code debugging.

Prior Art:

• disp in Matlab;
• The default print of Python and Julia;
• brief_print in Armadillo.

This PR will replace #520, and is related to #40, but is not sufficient to close #40.

Remaining to be discussed

• Is it necessary to support delimiters of any length, not just those with a length of 1? In addition to the print_array, it also includes the savetxt routine in stdlib_io.
• Currently, print_array is designed to assist users in program debugging and does not provide file write error reports like savetxt does.

[Copilot]

Pull Request Overview

This pull request adds a new subroutine specification, print_array, to the stdlib_io module for printing 2D arrays to an output unit.

• Introduces detailed documentation covering the subroutine’s syntax, argument descriptions, and an example.
• Specifies default behaviors for output unit, delimiter, format, and brief mode.

Files not reviewed (7)

• example/io/CMakeLists.txt: Language not supported
• example/io/example_print_array.f90: Language not supported
• src/CMakeLists.txt: Language not supported
• src/stdlib_io.fypp: Language not supported
• src/stdlib_io_print_array.fypp: Language not supported
• test/io/CMakeLists.txt: Language not supported
• test/io/test_print_array.f90: Language not supported