SSZ-QL: Optimize ParsePath for faster path parsing

[Sahil-4555]

What type of PR is this?

Other

What does this PR do? Why is it needed?
This PR refactors the ParsePath function to improve performance

Which issues(s) does this PR fix?
This PR addresses inefficiencies in ParsePath that caused extra allocations and slower path resolution. It enhances overall query execution performance within the #15767 feature.

Acknowledgements

• I have read CONTRIBUTING.md.
• I have included a uniquely named changelog fragment file.
• I have added a description to this PR with sufficient context for reviewers to understand this PR.

[Sahil-4555]

@syjn99 — since you contributed to the original ParsePath implementation, I’d really value your feedback on these optimizations. Please let me know if you spot any potential regressions or areas for further improvement.

goos: linux
goarch: amd64
pkg: github.com/OffchainLabs/prysm/v6/encoding/ssz/query
cpu: Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
                                       │ changes_bench.txt │          original_bench.txt          │
                                       │      sec/op       │   sec/op     vs base                 │
ParsePath/simple_path-8                        161.6n ± 9%   314.0n ± 5%   +94.37% (p=0.000 n=10)
ParsePath/path_with_leading_dot-8              174.2n ± 6%   327.4n ± 6%   +87.97% (p=0.000 n=10)
ParsePath/nested_arrays-8                      258.5n ± 3%   562.3n ± 2%  +117.52% (p=0.000 n=10)
ParsePath/deep_nested-8                        259.7n ± 3%   484.8n ± 7%   +86.69% (p=0.000 n=10)
ParsePath/path_with_multiple_indices-8         324.1n ± 4%   837.3n ± 4%  +158.33% (p=0.000 n=10)
geomean                                        227.7n        472.2n       +107.35%

                                       │ changes_bench.txt │         original_bench.txt          │
                                       │       B/op        │    B/op     vs base                 │
ParsePath/simple_path-8                         128.0 ± 0%   216.0 ± 0%   +68.75% (p=0.000 n=10)
ParsePath/path_with_leading_dot-8               144.0 ± 0%   232.0 ± 0%   +61.11% (p=0.000 n=10)
ParsePath/nested_arrays-8                       176.0 ± 0%   312.0 ± 0%   +77.27% (p=0.000 n=10)
ParsePath/deep_nested-8                         240.0 ± 0%   456.0 ± 0%   +90.00% (p=0.000 n=10)
ParsePath/path_with_multiple_indices-8          232.0 ± 0%   560.0 ± 0%  +141.38% (p=0.000 n=10)
geomean                                         178.4        331.3        +85.73%

                                       │ changes_bench.txt │          original_bench.txt          │
                                       │     allocs/op     │  allocs/op   vs base                 │
ParsePath/simple_path-8                         2.000 ± 0%    4.000 ± 0%  +100.00% (p=0.000 n=10)
ParsePath/path_with_leading_dot-8               2.000 ± 0%    4.000 ± 0%  +100.00% (p=0.000 n=10)
ParsePath/nested_arrays-8                       4.000 ± 0%    8.000 ± 0%  +100.00% (p=0.000 n=10)
ParsePath/deep_nested-8                         2.000 ± 0%    5.000 ± 0%  +150.00% (p=0.000 n=10)
ParsePath/path_with_multiple_indices-8          5.000 ± 0%   11.000 ± 0%  +120.00% (p=0.000 n=10)
geomean                                         2.759         5.882       +113.15%

[syjn99]

Hey, thanks for optimizing!