[kotlin] Reuse applicability checker between extension candidates

Before, auto-completion was based on on-air resolve, and
'FirTowerDataContext' was computed once, during creation of the
dependent analysis session (with using 'FirTowerDataContextCollector').
This allowed to return the context almost instantly, no matter how many
completion candidates there were.

Dangling file resolution doesn't use 'FirTowerDataContextCollector', as
now there is more precise 'ContextCollector'. However,
'ContextCollector' doesn't cache results by itself, and, if asked, it
will compute the same context over and over again. This exact happened
with extension applicability checker.

The optimized implementation maintains a checker object which caches the
computed context. The old end-point is left to give the IDE plugin time
to adapt to the change.

^KTIJ-28445

analysis/analysis-api-fe10/src/org/jetbrains/kotlin/analysis/api/descriptors/components/KtFe10CompletionCandidateChecker.kt

@@ -7,11 +7,11 @@ package org.jetbrains.kotlin.analysis.api.descriptors.components
 
 import org.jetbrains.kotlin.analysis.api.components.KtCompletionCandidateChecker
 import org.jetbrains.kotlin.analysis.api.components.KtExtensionApplicabilityResult
+import org.jetbrains.kotlin.analysis.api.components.KtCompletionExtensionCandidateChecker
 import org.jetbrains.kotlin.analysis.api.descriptors.KtFe10AnalysisSession
 import org.jetbrains.kotlin.analysis.api.descriptors.components.base.Fe10KtAnalysisSessionComponent
 import org.jetbrains.kotlin.analysis.api.symbols.KtCallableSymbol
 import org.jetbrains.kotlin.analysis.api.lifetime.KtLifetimeToken
-import org.jetbrains.kotlin.analysis.api.lifetime.withValidityAssertion
 import org.jetbrains.kotlin.psi.KtExpression
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.psi.KtSimpleNameExpression
@@ -22,6 +22,15 @@ internal class KtFe10CompletionCandidateChecker(
     override val token: KtLifetimeToken
         get() = analysisSession.token
 
+    override fun createExtensionCandidateChecker(
+        originalFile: KtFile,
+        nameExpression: KtSimpleNameExpression,
+        explicitReceiver: KtExpression?
+    ): KtCompletionExtensionCandidateChecker {
+        throw NotImplementedError("Method is not implemented for FE 1.0")
+    }
+
+    @Suppress("OVERRIDE_DEPRECATION")
     override fun checkExtensionFitsCandidate(
         firSymbolForCandidate: KtCallableSymbol,
         originalFile: KtFile,