Kotlin functions and identifiers with backticks are not highlighted correctly

[uberto]

This is a regression for #906 and #996

Name of the lexer
Kotlin lexter

Code sample
A sample of the code that produces the bug.

@Test
fun `adding one and two gives three`(){
  assertEquals(3, 1+2)
}

It also helps if you can provide a link to a code sample on rouge.jneen.net.

Additional context

It seems to be related with removing the regex

name_backtick = %r'#{name}|`#{name}`'

[tancnle]

Relates to #1326

[sbrannen]

• related to User guide highlights Java and Kotlin code wrong junit-team/junit5#3287