Make @Throws getter functions properties

[jeffdgr8]

This align's Kotbase's API with how the Couchbase Lite Java SDK appears in Kotlin, allowing for more seamless adoption of Kotbase with existing Kotlin code using Couchbase Lite. It also makes the APIs more idiomatic.

Note: this is a source-incompatible (but binary compatible, at least on JVM) change from Kotbase 3.0.x.

Instead of:

database.getIndexes()
replicator.getPendingDocumentIds()

now:

database.indexes
replicator.pendingDocumentIds

Most affected APIs are still unreleased until 3.1.

This change requires working around KT-63047, so these APIs do not appear as error throwing in native code. But the common Kotlin and JVM APIs are annotated @get:Throws.

It's expected the primary usage for the APIs is in common Kotlin code, but for Objective-C, the properties are hidden with @HiddenFromObjC and functions annotated @Throws are provided to allow for error handling in Swift and Objective-C.

// in Swift
try database.indexes()
try replicator.pendingDocumentIds()