Add Unicode 15.1.0 in Lib/unicode/, 246.82M

Add Unicode 15.1.0 in Lib/unicode/, 246.82M

Everything from <ftp://ftp.unicode.org/Public/15.1.0/>.

Copy+paste of the announcement at
<https://blog.unicode.org/2023/09/announcing-unicode-standard-version-151.html>:

> Tuesday, September 12, 2023\
> **Announcing The Unicode® Standard, Version 15.1**
>
> Version 15.1 of the Unicode Standard is now available. This minor
> version update includes updated code charts, data files and annexes.
> The core specification is unchanged from Unicode Version 15.0.
>
> This version adds 627 characters, bringing the total number of
> characters to 149,813. The additions include [622 CJK unified
> ideographs](http://blog.unicode.org/2023/08/622-new-cjk-ideographs-to-be-available.html)
> in a new block, CJK Unified Ideographs Extension I. These new
> ideographs are urgently needed in China for use in public service
> databases, and are expected to be included in a forthcoming amendment
> to China’s GB 18030-2022 standard. The other new characters are five
> ideographic description characters that enhance the ability to
> describe rare or not-yet-encoded CJK ideographs.
>
> There are six completely new emoji, such as for phoenix and lime and
> (finally) an edible mushroom. For 108 people emoji, you can now switch
> the direction that they are facing (for example, *person walking
> facing right* versus *facing left*).
>
> Security-related updates have been made to [UAX
> \#9](https://www.unicode.org/reports/tr9/tr9-48.html), *Unicode
> Bidirectional Algorithm* and [UAX
> \#31](https://www.unicode.org/reports/tr31/tr31-39.html), *Unicode
> Identifiers and Syntax* along with updates to [UTS
> \#39](https://www.unicode.org/reports/tr39/tr39-28.html), *Unicode
> Security Mechanisms*. These updates complement the release of a new
> Unicode Technical Standard, [UTS
> \#55](https://www.unicode.org/reports/tr55/tr55-3.html), *Unicode
> Source Code Handling*.
>
> The new characters are limited to three blocks, and the code charts
> for several other blocks have changed. The most significant change to
> charts is for the CJK Unified Ideographs, CJK Unified Ideographs
> Extension A and CJK Unified Ideographs Extension B blocks with the
> addition of representative glyphs and source references for over
> 24,000 KP-source (North Korea) ideographs. There are also many other
> glyph corrections and improvements—see the [15.1 delta code
> charts](https://www.unicode.org/charts/PDF/Unicode-15.1/) for details.
>
> Significant updates have been made to UAX \#14, *Unicode Line Breaking
> Algorithm* and UAX \#29, *Unicode Text Segmentation* adding better
> support for scripts of South and Southeast Asia, including grapheme
> cluster support for aksaras and consonant conjuncts, and line breaking
> at orthographic syllable boundaries.
>
> For complete details on Unicode Version 15.1, see
> <https://www.unicode.org/versions/Unicode15.1.0/>.

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