fix: Bug in JDTCommentBuilder

[Egor18]

Hi! I've found some funny bug in JDTCommentBuilder. Model building fails with the following exception:

spoon.SpoonException: Unexpected next line after last line
	at spoon.support.compiler.jdt.JDTCommentBuilder.cleanComment(JDTCommentBuilder.java:595)
	at spoon.support.compiler.jdt.JDTCommentBuilder.getCommentContent(JDTCommentBuilder.java:557)
	at spoon.support.compiler.jdt.JDTCommentBuilder.buildComment(JDTCommentBuilder.java:143)
	at spoon.support.compiler.jdt.JDTCommentBuilder.build(JDTCommentBuilder.java:108)

on this code:

class Test {
     /*/
     Hello!
     */
}

The problem is that */ from /*/ is considered as the end of the comment. This PR provides possible solution and some additional tests.

[pvojtechovsky]

Could you please move all these new comment examples above (to line >116). This test expects pairs of tested comment example and expected string content of the comment.

[Egor18]

Should I create a new file for them?

[pvojtechovsky]

new file

no, just move them up and add expected content of the comment text. For example:
convert this

/*/
slash and comment
*/

to

/*/
slash and comment
*/
"/\nslash and comment"

[pvojtechovsky]

Thank You 👍