core.expr: implement hex numbers

[alexanderpann]

This is a more editor-heavy reimplementation of https://github.com/IETS3/iets3.opensource/pull/630 that is hopefully is not a breaking change anymore. There is only a small issue that when you create a hex value in the max field in the range specs the cursor jumps to the min field afterwards. I couldn't fix this issue but it is only a small inconvenience. See previous PR for a screenshot. The approach can be adapted for any string properties that are used for storing numbers.

Changes:

• Number literals, collection size specifications and number range specifications now support entering numbers in hexadecimal format. This feature can be deactived through PrimitiveTypeMapper#allowHexadecimalNumbers.
• Collection size and number range specifications now initialize with an infinite range by default. Setting the min and max field therefore is equal to setting them to infinity.