Make it possible to create multiple words with the same text

[nya-elimu]

Currently, it is not possible to add a word if another word with the same text value already exists in the database.

Change this, to make it possible to add another word with an identical text value, but different meaning/pronunciation.

For example, the English word "can" can be both a verb and a noun. Refactor the code, to make it possible to store both.

[tomaszsmy]

https://github.com/elimu-ai/webapp/pull/1582 Now can be added the same word but with other word type please check if I haven't missed any place in application.