Fix common collection cases of UnusedAssertionDetector

[jzbrooks]

assertThat(list.contains("Foo")) replaced with assertThat(list).contains("Foo")

Considering other relevant cases here:
https://github.com/willowtreeapps/assertk/blob/main/assertk/src/commonMain/kotlin/assertk/assertions/list.kt
https://github.com/willowtreeapps/assertk/blob/main/assertk/src/commonMain/kotlin/assertk/assertions/iterable.kt

[jzbrooks]

Relates to #72