Add fixes to the project

[OleksandrOrlovIT]

add constant for strings methods in dao layer.

@Transactional deleteByUsername

Pageable add to getTrainersWithoutPassedTrainee

Delete log.info findByUsername dao

findByids IllegalArgumentException

add newline to new facade classes

fix entities using Lombok

threadLocal instead of simple User class in authenticationService

change getTrainingByDateTraineeName

decide get or select of find

all methods start from verb

10 to const in services

in optional change ifs to orElseThrow

properties delete update for hibernateProperties

change config to read property files

change test names to use camelCase and start with method name

add assertTrue when create entity in tests

add new line in classes without it

add space between brackets

delete update from db properties

[OleksandrOrlovIT]

Pageable add to getTrainersWithoutPassedTrainee

properties delete update for hibernateProperties

change config to read property files

change test names to use camelCase and start with method name

add assertTrue when create entity in tests

add new line in classes without it

add space between brackets

delete update from db properties