[mojo-stdlib] Removed constructor from Stringable

[StandinKP]

Fixes #2169

Merge after:

• [mojo-stdlib] Used explicit str in _location.mojo #2562
• [mojo-stdlib] Used explicit str in float_literal.mojo #2563
• [mojo-stdlib] Used explicit str in int_literal.mojo #2564
• [mojo-stdlib] Used explicit str in os.mojo #2565
• [mojo-stdlib] Used explicit str in string.mojo #2566
• [mojo-stdlib] Used explicit str in list.mojo #2567
• [mojo-stdlib] Used explicit str in testing.mojo #2568
• [mojo-stdlib] Used explicit str in inlined_string.mojo #2569
• [mojo-stdlib] Used explicit str in test_error.mojo #2570
• [mojo-stdlib] Used explicit str in test_file.mojo #2571
• [mojo-stdlib] Used explicit str in test_object.mojo #2572
• [mojo-stdlib] Used explicit str in test_simd.mojo #2573
• [mojo-stdlib] Used explicit str in test_string.mojo #2574
• [mojo-stdlib] Used explicit str in test_dict.mojo #2575
• [mojo-stdlib] Used explicit str in test_remove.mojo #2576
• [mojo-stdlib] Used explicit str in test_python_interop.mojo #2577
• [mojo-stdlib] Used explicit str in test_format.mojo #2578

[StandinKP]

@JoeLoser is this also merged?

[JoeLoser]

@JoeLoser is this also merged?

This has not been merged yet internally. The PR here will auto close when it is. I fixed 50 or so occurrences yesterday, but we still have a ton more internally to fix before we can remove this constructor. I may mark it as deprecated to motivate folks internally to update their code so I'm not in the business of fixing the whole codebase for every stdlib change :)

[JoeLoser]

@Dan13llljws just fixed the rest of the internal sites to land this work. Thank you, everyone!