Introduce and test `UtBotSpringApi`

[IlyaMuravjov]

Description

Add UtBotSpringApi that helps UtBotJavaApi users create SpringApplicationContext to run Spring-specific test generation (see #2614)

How to test

Automated tests

The proposed changes are verified with tests: utbot-spring-test/src/test/java/org/utbot/examples/spring/manual/UtBotSpringApiTest.java

Self-check list

• [x] I've set the proper labels for my PR (at least, for category and component).
• [x] PR title and description are clear and intelligible.
• [x] I've added enough comments to my code, particularly in hard-to-understand areas.
• [x] The functionality I've repaired, changed or added is covered with automated tests.
• [ ] Manual tests have been provided optionally.
• [x] The documentation for the functionality I've been working on is up-to-date.