Avoid whole source reparsing when the IDE performs a simple edit

[JaroslavTulach]

Pull Request Description

The goal of this PR is to demonstrate we can avoid parsing of the whole program when the IDE makes simple edit. The PR contains new [IncrementalUpdatesTest](https://github.com/enso-org/enso/compare/wip/jtulach/IncrementalUpdates-182323784?expand=1#diff-225738cc33a66aea979256736e4467473c6d5a4e0b16efe821caac3c1f4730c1) which (via NodeCountingTestInstrument) checks whether a new node is created or not. Right now the test fails with an error 28 nodes created instead of none when replacing 4 with 5:

No new nodes created. Maximal size should be 0, but was: 28 in
[error] org.enso.interpreter.node.expression.constant.DynamicSymbolNode @ Enso_Test.Test.Main:8
[error] org.enso.interpreter.node.expression.constant.DynamicSymbolNode @ Enso_Test.Test.Main:9
[error] org.enso.interpreter.node.expression.literal.IntegerLiteralNode @ Enso_Test.Test.Main:4
[error] org.enso.interpreter.node.callable.ApplicationNode @ Enso_Test.Test.Main:8
[error] org.enso.interpreter.node.callable.ApplicationNode @ Enso_Test.Test.Main:9
[error] org.enso.interpreter.node.callable.thunk.ForceNodeGen @ Enso_Test.Test.Main:5
[error] org.enso.interpreter.node.callable.argument.ReadArgumentNode
[error] org.enso.interpreter.node.callable.argument.ReadArgumentNode
[error] org.enso.interpreter.node.callable.function.StatementNode @ Enso_Test.Test.Main:7
[error] org.enso.interpreter.node.callable.function.StatementNode @ Enso_Test.Test.Main:8
[error] org.enso.interpreter.node.callable.function.StatementNode @ Enso_Test.Test.Main:3
[error] org.enso.interpreter.node.callable.function.StatementNode @ Enso_Test.Test.Main:4
[error] org.enso.interpreter.node.callable.function.StatementNode
[error] org.enso.interpreter.node.callable.function.StatementNode
[error] org.enso.interpreter.node.callable.function.BlockNode
[error] org.enso.interpreter.node.callable.function.BlockNode @ Enso_Test.Test.Main:7
[error] org.enso.interpreter.node.callable.function.BlockNode
[error] org.enso.interpreter.node.callable.function.BlockNode @ Enso_Test.Test.Main:3
[error] org.enso.interpreter.node.callable.FunctionCallInstrumentationNode @ Enso_Test.Test.Main:8
[error] org.enso.interpreter.node.callable.FunctionCallInstrumentationNode @ Enso_Test.Test.Main:9
[error] org.enso.interpreter.node.expression.constant.ConstructorNodeGen @ Enso_Test.Test.Main:8
[error] org.enso.interpreter.node.expression.constant.ConstructorNodeGen @ Enso_Test.Test.Main:9
[error] org.enso.interpreter.node.scope.ReadLocalVariableNodeGen @ Enso_Test.Test.Main:5
[error] org.enso.interpreter.node.scope.ReadLocalVariableNodeGen @ Enso_Test.Test.Main:9
[error] org.enso.interpreter.node.scope.AssignmentNodeGen
[error] org.enso.interpreter.node.scope.AssignmentNodeGen @ Enso_Test.Test.Main:8
[error] org.enso.interpreter.node.scope.AssignmentNodeGen
[error] org.enso.interpreter.node.scope.AssignmentNodeGen @ Enso_Test.Test.Main:4, took 5.622 sec
[error] Failed: Total 1, Failed 1, Errors 0, Passed 0

The 8bd50ab commit fixes the test by finding the right IntegerLiteralNode in the Truffle AST and updating it.

Important Notes

Checklist

Please include the following checklist in your PR:

• All code conforms to the
  Scala,
  Java,
  and
  Rust
  style guides.
• All code has been tested:
  • Unit tests have been written where possible.

[kustosz]

Quite elegant, though we definitely should update the IR as well. Also a few remarks inline

[kustosz]

Logically this seems right, some comments left inline.

[4e6]

Nicely done! Please clean things up a bit before we merge it

[JaroslavTulach]

Commit 6c81820 addressed the latest comments. I am not sure what to do about #3508 (comment) - as there already is suggested small change in a single literal or {@code null} which describes what the parameter is used for.

Adding "CI: Ready to merge" label. Awaiting approval.

[4e6]

A few more comments by me, but overall looks good now!

[hubertp]

I think we let you suffer enough of Scala, just make sure numericValue returns Either and it lgtm