Description

This PR cleans up the code surrounding formatting and displaying file sizes.

• The byte_unit crate we use for file size units displays kilobytes as KB, which is not the SI or ISO/IEC standard. Rather it should be kB, so this fixes SI Kilobyte should be written as "kB", not "KB" #8872. On some systems, KB actually means KiB, so this avoids any potential confusion.
• The byte_unit crate, when displaying file sizes, casts integers to floats which will lose precision for large file sizes. This PR adds a custom Display implementation for Filesize that can give an exact string representation of a Filesize for metric/SI units.
• This PR also removes the dependency on the byte_unit crate which brought in several other dependencies.

Additionally, this PR makes some changes to the config for filesize formatting ($env.config.filesize).

• The previous filesize config had the metric and format options. If a metric (SI) unit was set in format, but metric was set to false, then the metric option would take precedence and convert format to the corresponding binary unit (or vice versa). E.g., { format: kB, metric: false } => KiB. Instead, this PR adds the unit option to replace the format and metric options. unit can be set to a fixed file size unit like kB or KiB, or it can be set to one of the special options: binary or metric. These options tells nushell to format file sizes using an appropriately scaled metric or binary unit (examples below).

  # precision = null
  
  # unit = kB
  1kB  # 1 kB
  1KiB # 1.024 kB
  
  # unit = KiB
  1kB  # 0.9765625 KiB
  1KiB # 1 KiB
  
  # unit = metric
  1000B     # 1 kB
  1024B     # 1.024 kB
  10_000MB  # 10 GB
  10_240MiB # 10.73741824 GB
  
  # unit = binary
  1000B     # 1000 B
  1024B     # 1 KiB
  10_000MB  # 9.313225746154785 GiB
  10_240MiB # 10 GiB

• In addition, this PR also adds the precision option to the filesize config. It determines how many digits to show after the decimal point. If set to null, then everything after the decimal point is shown.
• The default filesize config is { unit: metric, precision: 1 }.

User-Facing Changes

• Commands that use the config to format file sizes will follow the changes described above (e.g., table, into string, to text, etc.).
• The file size unit/format passed to format filesize is now case sensitive. An error with the valid units is shown if the case does not match.
• $env.config.filesize.format and $env.config.filesize.metric are deprecated and replaced by $env.config.filesize.unit.
• A new $env.config.filesize.precision option was added.

Tests + Formatting

Mostly updated test expected outputs.

After Submitting

This PR does not change the way NUON serializes file sizes, because that would require changing the nu parser to be able to losslessly decode the new, exact string representation introduced in this PR.

Similarly, this PR also does not change the file size parsing in any way. Although the file size units provided to format filesize or the filesize config are now case-sensitive, the same is not yet true for file size literals in nushell code.