[application.properties] improve sorting of content-assist property proposals while typing

[martinlippert]

This is specific to Eclipse (it works much better in VSCode).

When tying serverpor, the list of proposals looks counter-intuitive. The proposal for server.port shows up, but before, there are a number of other proposals in that list that contain the characters, but should be ranked a lot lower.

This seems to be the case when there is no . typed in the editor. When the user types server.por, the list looks much better.

Another example:

• springtask shows up with a weird ranking of proposals
• spring.task shows up with a nice ranking of the proposals