Align Kotlin Native targets with Kotlin documentation (#2560)

This commit moves the 'linuxX64' target to tier 2 and reorders targets of this tier.

References: 
https://kotlinlang.org/docs/native-target-support.html
https://kotlinlang.org/docs/whatsnew1920.html#change-to-our-target-tiers-policy
https://youtrack.jetbrains.com/issue/KT-58711

gradle/native-targets.gradle

@@ -11,13 +11,14 @@ kotlin {
 
         // According to https://kotlinlang.org/docs/native-target-support.html
         // Tier 1
-        linuxX64()
         macosX64()
         macosArm64()
         iosSimulatorArm64()
         iosX64()
 
         // Tier 2
+        linuxX64()
+        linuxArm64()
         watchosSimulatorArm64()
         watchosX64()
         watchosArm32()
@@ -26,7 +27,6 @@ kotlin {
         tvosX64()
         tvosArm64()
         iosArm64()
-        linuxArm64()
 
         // Tier 3
         mingwX64()