[lldb-dap] Refactor variablesReference storage and scope management. (#179262)HEADmain

This commit refactors the Variables class into a
VariableReferenceStorage with variableReferences of different
ReferenceKinds.

The variablesReference is now a uint32_t.
The most significant byte (bits 24 - 31) holds the reference kind and
the remaining 3 bytes (bits 0 -23) holds the actual reference.

We have (at the moment) 3 reference kinds.
Temporary => 0b0000 => 0x00
Permanent => 0b0001 => 0x01
Scope     => 0b0010 => 0x03

The actual variablesReference can be used to get a `VariableStore`.

VariableStore holds variables in a group.
It has two implementations:
- ScopeStore: Holds variables within frame scopes (locals, globals,
registers). This is lazy-loaded and only fetched when variable(s) in the
scope is requested.
- ExpandableValueStore: Holds SBValue and fetches it's variable children
when requested.

ReferenceKindPool:
   The variablesReference created starts from 1 with the mask of the
   Reference kind applied.
   It holds vector of VariableStore of one Referencekind,
   This allows constant lookup of a reference

Example:
```md

| maskedVariablesReference | Mask | variablesReference | RefrenceKind | VariableStore |
|--------------------------|------|--------------------|--------------|---------------|
| 20        -> 0x00000014  | 0x00 | 20 -> 0x00000014   | temporary    | ValueStore    |
| 268435476 -> 0x01000014  | 0x01 | 20 -> 0x00000014   | permanent    | ValueStore    |
| 536870932 -> 0x01000014  | 0x02 | 20 -> 0x00000014   | scope        | ScopeStore    |
```

0 files changed, 0 insertions, 0 deletions