Add a tool for generating character width tables

Summary:
The uni2characterwidth tool, converts Unicode Character Database files
into character width lookup tables. It uses a template file to place
the tables in a source code file together with a function for finding
the width for specified character. It also allows to generate few forms
of lists with width data for debug and test purposes, or for future use
as a replacement of Unicode files.

Set `KONSOLE_BUILD_UNI2CHARACTERWIDTH` cmake flag to build the tool.
Use `--help` argument for more detailed usage.

There is a possibility to generate separate "width" for Ambiguous
characters. It can be used to add ability to configure the characters
width in Konsole settings.

The `example.template` file contains all possible named tags, and some
additional tags to show how to use them.

CCBUG: 396435

Depends on D15756

Test Plan:
Download files listed below from `11.0.0` and `emoji/11.0` directories
on `https://unicode.org/Public/`. You can also directly use URLs to the
files.

* UnicodeData.txt
* EastAsianWidth.txt
* emoji-data.txt

Generate any available list except compact-ranges (e.g. `details`):

```
uni2characterwidth \
    -U UnicodeData.txt  -A EastAsianWidth.txt  -E emoji-data.txt \
    -g details  result.txt
```

The list should contain ranges for all possible widths
(-2, -1, 0, 1, 2). You can choose some characters with a width you know
and check how they were classified. -2 is a special non-standard width
for ambiguous characters, which can be overriden by adding `-a 1` or
`-a 2` parameter. With this flag, all ranges from -2 group should
disappear and become assigned to selected width (1 or 2).

Generate output using a template:

```
uni2characterwidth \
    -U UnicodeData.txt  -A EastAsianWidth.txt  -E emoji-data.txt \
    -g code,./template.example  result.txt
```

Reviewers: #konsole, hindenburg

Reviewed By: #konsole, hindenburg

Subscribers: hindenburg, konsole-devel

Tags: #konsole

Differential Revision: https://phabricator.kde.org/D15757