Lower mbstring dep, remove it for Yaml and CssSelector components
[Console]Improve formatter for double-width character
bug #10714 [Console]Improve formatter for double-width character (denkiryokuhatsuden)

This PR was squashed before being merged into the 2.3 branch (closes #10714).

Discussion
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[Console]Improve formatter for double-width character

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | yes for one that expecting current broken output
| Deprecations? | no
| Fixed tickets |
| Tests pass?   | yes
| License       | MIT
| Doc PR        |

EDIT: fixed the table above not to remove irrelevant line

As mb_strlen just returns "how many chars in the string",
formatting with double-width character is bit broken.

The test I add is skipped when mbstring extension is not loaded.
I'm afraid if some of you cannot properly display japanese string.
(表示するテキスト just means "Some text to display")

Commits
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a52f41d [Console]Improve formatter for double-width character
minor #10890 Lower mbstring dep, remove it for Yaml and CssSelector components (nicolas-grekas)

This PR was merged into the 2.3 branch.

Discussion
----------

Lower mbstring dep, remove it for Yaml and CssSelector components

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | yes
| Tests pass?   | yes
| Fixed tickets | none
| License       | MIT
| Doc PR        | none

Commits
-------

a4b805d Lower mbstring dep, remove it for Yaml and CssSelector components