Introduced sigma-data module

[aslesarenko]

In this PR:

• AvlTreeVerifier into separate file
• cleanup code + v6.0 todos
• Value class moved to sigma.ast package
• partially removed code related to TaggedVar
• types, JitCost, CostKind, Operations, SMethod, trees, transformers, serializers moved to sigma.ast package of data module
• SparseArrayContainer.scala moved to sigma.utils
• introduced ErgoTreeEvaluator, Profiler, AvlTreeVerifier interfaces
• js.ErgoTree moved to sigma-data module
• Added missing ScalaDocs

[kushti]

defs name is not descriptive, Scala code conventions not followed, ScalaDoc missed

[kushti]

ScalaDocs missed in the class

[aslesarenko]

1. Please suggest a name.
2. Which exactly conventions not followed?

[kushti]

Without ScalaDocs I can't really answer (1), on (2), naming could be ok actually if object is mimicking a package, but hard to say if this is the case, again, without description

[aslesarenko]

ok, renamed to syntax and added ScalaDocs

[kushti]

ScalaDocs missed

[aslesarenko]

This class turns out to be duplicated, removed.

[kushti]

unused import

[aslesarenko]

removed

[kushti]

unused import

[aslesarenko]

removed

[kushti]

Unused code after this PR:

  /** Helper extractor to match SigmaProp values and extract ProveDlog out of it. */
  object ProveDlogProp {
    def unapply(p: SigmaProp): Option[ProveDlog] = SigmaDsl.toSigmaBoolean(p) match {
      case d: ProveDlog => Some(d)
      case _ => None
    }
  }