GH-2350 Support underscore character in the not found page template

Author: dzikoysk

reposilite-backend/src/main/kotlin/com/reposilite/frontend/NotFoundTemplate.kt

@@ -21,7 +21,7 @@ import org.intellij.lang.annotations.Language
 object NotFoundTemplate {
 
     private val uriFormatter = Regex("/+") // exclude common typos from URI
-    private val regexAntiXss = Regex("[^A-Za-z0-9/.\\- ]") // exclude custom non-standard characters from template
+    private val regexAntiXss = Regex("[^A-Za-z0-9/.\\-_ ]") // exclude custom non-standard characters from template
 
     fun createNotFoundPage(basePath: String, originUri: String, details: String): String {
         val uri = originUri.replace(uriFormatter, "/")

reposilite-backend/src/test/kotlin/com/reposilite/storage/LocationTest.kt

@@ -30,6 +30,7 @@ class LocationTest {
         assertThat(Location.of("/group").resolve("/artifact").toString()).isEqualTo("group/artifact")
         assertThat(Location.of("/////group/////").resolve("/////artifact/////").toString()).isEqualTo("group/artifact")
         assertThat(Location.of("\\\\\\group\\\\\\").resolve("\\\\\\artifact\\\\\\").toString()).isEqualTo("group/artifact")
+        assertThat(Location.of(".abc").resolve("_cdf.efg").toString()).isEqualTo(".abc/_cdf.efg")
         assertThat(Location.of("시험").resolve("기준").toString()).isEqualTo("시험/기준")
     }