Add support for char element to dto factory

To avoid the notice "Types char is not declared" (which breaks setup:upgrade)
when using the very type anywhere in the MySQL database, mapping for this specific type
is added to the DI as well.

Author: wardcapp

app/etc/di.xml

@@ -1435,6 +1435,7 @@
                 <item name="mediumtext" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Dto\Factories\MediumText</item>
                 <item name="text" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Dto\Factories\Text</item>
                 <item name="varchar" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Dto\Factories\StringBinary</item>
+                <item name="char" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Dto\Factories\StringBinary</item>
                 <item name="varbinary" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Dto\Factories\StringBinary</item>
                 <item name="blob" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Dto\Factories\Blob</item>
                 <item name="mediumblob" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Dto\Factories\MediumBlob</item>