[lworld] RFR: 8377451: [lworld] Add ValuePayload abstraction [v5]

[Axel Boldt-Christmas]

> Create a wrapper class which represents the payload of an InlineKlass object.
> 
> The current convention is to use a `void*` representing where the payload starts, the `InlineKlass*` (as we do not always have a header when flattened) and a `LayoutKind` (describing the payloads layout). 
> 
> I suggest we introduce something like a `ValuePayload` which encapsulate these properties. As well as a hierarchy built upon these, with the proper interfaces implemented.
> * ValuePayload (Any payload)
>   * RawValuePayload (Payload with holder erased)
>   * BufferedValuePayload (Payload of normal heap object)
>   * FlatValuePayload (Payload of flattened value)
>     * FlatFieldPayload (Payload of flattened field)
>     * FlatArrayPayload (Payload of flattened array element)
>    
> The goal is to both make interfaces clearer, and easier to understand. As well as consolidating the implementation in one place rather than spread across different subsystems. 
> 
> Each type (except RawValuePayload) also allows for the creation of a Handle, (thread local, or in an OopStorage) for keeping the payload as a thread or global root.
> 
> The ValuePayload class is also the interface for interacting with the Access API for InlineKlass objects.
> 
> * Testing
>   * Running tier 1-4 with preview enabled
>   * Running app tests with preview enabled
>   * Running normal tier 1-5 
> 
> #### _Extra Notes:_
>  * The `OopHandle` type is there so that we can migrate the JVMTI payload abstraction implementation to using this instead. (Future RFE)
>  * Some interfaces got cleaned up. Some are unused. Like the `null_payload` which was superseded by the `Access::value_store_null`. C1 still uses the `.null_reset` but if that dependency is removed we should be able to remove that weird object all together.
>  * Simply adding the Java to VM transition deep inside the payload code created a circular include dependency here. So rather than fixing that, I implemented the relevant bytecodes in the BytecodeInterpreter.

Axel Boldt-Christmas has updated the pull request incrementally with two additional commits since the last revision:

 - Avoid having to align label entires
 - Fix BytecodeInterpreter dispatch table

-------------

Changes:
  - all: https://git.openjdk.org/valhalla/pull/2068/files
  - new: https://git.openjdk.org/valhalla/pull/2068/files/bcebec6f..342cd358

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=2068&range=04
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=2068&range=03-04

  Stats: 335 lines in 1 file changed: 255 ins; 0 del; 80 mod
  Patch: https://git.openjdk.org/valhalla/pull/2068.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2068/head:pull/2068

PR: https://git.openjdk.org/valhalla/pull/2068