adds better error for failed string-to-duration conversions

[merelymyself]

Description

Fixes #5975. New error can probably be used for other issues of a similar kind.

Tests

Make sure you've done the following:

• Add tests that cover your changes, either in the command examples, the crate/tests folder, or in the /tests folder.
• Try to think about corner cases and various ways how your changes could break. Cover them with tests.
• If adding tests is not possible, please document in the PR body a minimal example with steps on how to reproduce so one can verify your change works.

/home/gabriel/CodingProjects/nushell〉echo [[value]; ['1.1ms'] ['12s'] ['2min'] ['3hr'] ['4day'] ['5wk']] | into duration value     07/07/2022 04:49:40 PM
Error: nu::shell::cant_convert_with_value (link)

  × Can't convert to duration.
   ╭─[entry #1:1:1]
 1 │ echo [[value]; ['1.1ms'] ['12s'] ['2min'] ['3hr'] ['4day'] ['5wk']] | into duration value
   ·                                                                       ──────┬──────
   ·                                                                             ╰── can't convert string `12s` to duration
   ╰────
  help: supported units are ns, us, ms, sec, min, hr, day, and wk

Make sure you've run and fixed any issues with these commands:

• cargo fmt --all -- --check to check standard code formatting (cargo fmt --all applies these changes)
• cargo clippy --workspace --features=extra -- -D warnings -D clippy::unwrap_used -A clippy::needless_collect to check that you're using the standard code style
• cargo test --workspace --features=extra to check that all the tests pass

[WindSoilder]

What about making error message like this? It seems more intuitive to me

Error: nu::shell::cant_convert (link)

  × Can't convert to duration.
   ╭─[entry #2:1:1]
 1 │ echo [[value]; ['1.1ms'] ['12s'] ['2min'] ['3hr'] ['4day'] ['5wk']] | into duration value
   ·                           ──┬──
   ·                             ╰── can't convert string to duration
   ╰────
  help: supported units are ns, us, ms, sec, min, hr, day, and wk

[merelymyself]

@WindSoilder - with the new commit, I guess I met you in the middle? I still think the operator should be labelled, in accordance with all other nushell errors, but your suggestion was good as well, so now both are labelled. And in case there's a labelling error, the error header still gives all the info necessary

/home/gabriel/CodingProjects/nushell〉echo [[value]; ['1.1ms'] ['12s'] ['2min'] ['3hr'] ['4day'] ['5wk']] | into duration value    07/07/2022 06:19:54 PM
Error: nu::shell::cant_convert_with_value (link)

  × Can't convert string `12s` to duration.
   ╭─[entry #1:1:1]
 1 │ echo [[value]; ['1.1ms'] ['12s'] ['2min'] ['3hr'] ['4day'] ['5wk']] | into duration value
   ·                           ──┬──                                       ──────┬──────
   ·                             │                                               ╰── can't be converted to duration
   ·                             ╰── this string value...
   ╰────
  help: supported units are ns, us, ms, sec, min, hr, day, and wk

[fdncred]

I don't see any tests but I'm not sure there is a way to add tests for this? If you think of one please add it. Thanks.