This replaces numeric tag-based prefixes with the actual tag name.
While this means in general slightly larger trap files, it aids
debugging them for a human.
In the future we can make this conditional on some kind of trap debug
option, but for the moment it does not seem detrimental.
These changes are required to allow a new type-safe approach to TBD
nodes, that will come in a separate commit.
This introduces:
* the possibility to add properties to the root `Element`
* a functor taking tags to the corresponding binding trap entry
* `hasProp()` methods for optional properties in QL
* `getPrimaryQlClass()` method
Properties marked with `predicate` in the schema are now accepted.
* in the dbscheme, they will translate to a table with a single `id`
column (and the table name will not be pluralized)
* in C++ classes, they will translate to `bool` fields
* in QL classes, they will translate to predicates
Closes https://github.com/github/codeql-c-team/issues/1016
