[lldb] [disassembler] chore: enhance VariableAnnotator to return structured data: introduce VariableAnnotator::AnnotateStructured method (#169408)

## Description
Contribution to this topic [Rich Disassembler for
LLDB](https://discourse.llvm.org/t/rich-disassembler-for-lldb/76952),
this part.
```
The rich disassembler output should be exposed as structured data and made available through LLDB’s scripting API so more tooling could be built on top of this
```

----

This pr introduces new method `AnnotateStructured` in
`VariableAnnotator` class, which returns the result as a vector of
`VariableAnnotation` structured data, compared to original `Annotate`.

Additionally structured data is enhanced with information inferred from
`DWARFExpressionEntry` and variable declaration data.

I have moved this part of functionality form a bigger pr
https://github.com/llvm/llvm-project/pull/165163 to make it easier to
review, deliver smaller chunk faster in an incremental way.

## Testing
Run test with
```sh
./build/bin/lldb-dotest -v -p TestVariableAnnotationsDisassembler.py lldb/test/API/functionalities/disassembler-variables
```

all tests (9 existing) are passing.

<details>
<summary>screenshot 2025-11-24</summary>
<img width="1344" height="875" alt="screenshot"
src="https://github.com/user-attachments/assets/863e0fca-1e3e-43dc-bfa3-4b78ce287ae6"
/>
</details>


<details>
<summary>screenshot 2025-11-26</summary>
<img width="1851" height="865" alt="image"
src="https://github.com/user-attachments/assets/d47dacee-a679-4a49-ab22-efb5a16fe29c"
/>
</details>

<details>
<summary>screenshot 2025-12-03</summary>
<img width="1592" height="922" alt="Screenshot From 2025-12-03 22-11-30"
src="https://github.com/user-attachments/assets/957ded3d-bea1-43d0-8241-d342dfc2c7b0"
/>
</details>

---------

Signed-off-by: Nikita B <n2h9z4@gmail.com>
Co-authored-by: Jonas Devlieghere <jonas@devlieghere.com>