Add option to remove ANSI escape sequences from bat's input.

[eth-p]

This pull request introduces a new --strip-ansi option to bat.

This option tells bat whether to strip ANSI/VT escape sequences from the input file. The following values are supported:

• always: Always strip escape sequences.
• never: Never strip escape sequences. (default)
• auto: Strip escape sequences when printing any language that is not "Plain Text".
  This preserves bat's ability to print piped commands (or pre-highlighted files) and keep their existing colors.

Benchmarks

Disabled, Regular File

No significant difference.

Enabled, Regular File

A minor reduction in performance.

Disabled, Pre-highlighted File

No significant difference.

Enabled, Pre-highlighted File

It's certainly an improvement.

Auto Mode

The detection part of --strip-ansi=auto causes no significant difference when syntax highlighting is used.

However, it does add a few milliseconds of startup time when used with --color=never. This is because --strip-ansi=auto relies on detecting the syntax in order to determine if a file is plain text or not (and thus whether to strip the ANSI sequences).

TODO

• Support stripping sequences in SimplePrinter (maybe. thoughts?)
• ~~Wait for #2998. It contains the changes made in b4fe182960e45d4fd9ebd5ac2c4d2e4b4522b144, which this PR depends on.~~
• Update long_help integration test
• Write tests
• Benchmarks
• Run cargo fmt
• Allow --strip-ansi to be passed multiple times (so it can be set to auto in config and overridden on the cli)

[eth-p]

Rebased to c264ecd2 and fixed some clippy warnings.