pytest `snapshot_folder_name` and `allow_multiple_equivalent_writes_to_one_location`

- Original API documentation: https://kdoc.selfie.dev/selfie-runner-junit5/com.diffplug.selfie.junit5/-selfie-settings-a-p-i/

- Original junit5 implementation: https://github.com/diffplug/selfie/blob/main/jvm/selfie-runner-junit5/src/main/kotlin/com/diffplug/selfie/junit5/SelfieSettingsAPI.kt

- Original Kotest implementation: https://github.com/diffplug/selfie/blob/main/jvm/selfie-runner-kotest/src/commonMain/kotlin/com/diffplug/selfie/kotest/SelfieSettingsAPI.kt

- SelfieSettings example: https://github.com/diffplug/selfie/blob/main/jvm/example-junit5/src/test/java/selfie/SelfieSettings.java

Start with the linked original API documentation and the JUnit5 and Kotest SelfieSettingsAPI implementations, then review the linked SelfieSettings example. Determine the intended pytest equivalents for snapshot_folder_name and allow_multiple_equivalent_writes_to_one_location; done means both settings are available and covered by the pytest integration.

Written by the indexing model from the issue text.