Improve NON_KEYWORDS and other changes

[katzyn]

1. NON_KEYWORDS setting now works in more cases, for example, ROW now can be used as a column name with NON_KEYWORDS=ROW. Closes "ROW" cannot be set as a non keyword in 2.x #3390.
2. FILTER is removed from the list of context-sensitive keywords, because now only FILTER (WHERE has special meaning.
3. Arguments of methods in SpatialDataType are changed from Object to Spatial to reduce number of casts. Spatial is an interface from MVStore, so it can be used here without introduction of unwanted dependencies. Object was needed a long time ago to avoid usage of SpatialKey from H2.
4. DbObject.getCreateSQLForCopy() now has default implementation that throws an exception to significantly reduce number of its implementations, most of them also need to throw an exception.
5. Database.getTempTableName() now truncates too long names of identifiers.
6. Tables with custom table engines now can be only created by an user with ADMIN privileges like any other DDL operations with user-provided classes.