fix: comptime code not mutating shared ref to struct field

[jfecher]

Description

Problem*

Resolves #9154

Summary*

Fixes the issue by assigning to each struct/tuple field recursively during comptime which somewhat mimics SSA's flattening of tuple values.

Additional Context

I found a new issue while working on this in that the same code but using &mut instead of let mut returns false in acir.

So before this PR we had:

+---------+-------+----------+
|         | ACIR  | Comptime |
+---------+-------+----------+
| let mut | true  | false    |
| &mut    | false | false    |
+---------+-------+----------+

And after it we have:

+---------+-------+----------+
|         | ACIR  | Comptime |
+---------+-------+----------+
| let mut | true  | true     |
| &mut    | false | true     |
+---------+-------+----------+

But we want them all to be true.
I've created a separate issue for the &mut issue in ACIR here: #9251

Documentation*

Check one:

• No documentation needed.
• Documentation included in this PR.
• [For Experimental Features] Documentation to be submitted in a separate PR.

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'Execution Time'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.20.

Benchmark suite	Current: cfe5fd6	Previous: 80b04ec	Ratio
private-kernel-inner	0.017 s	0.014 s	1.21
sha512-100-bytes	0.101 s	0.056 s	1.80

This comment was automatically generated by workflow using github-action-benchmark.

CC: @TomAFrench

[asterite]

Looks good!

[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'Compilation Time'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.20.

Benchmark suite	Current: cfe5fd6	Previous: 80b04ec	Ratio
rollup-block-root-empty	28.7 s	20.7 s	1.39

This comment was automatically generated by workflow using github-action-benchmark.

CC: @TomAFrench

[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'Test Suite Duration'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.20.

Benchmark suite	Current: cfe5fd6	Previous: 80b04ec	Ratio
test_report_zkpassport_noir_rsa_	2 s	1 s	2

This comment was automatically generated by workflow using github-action-benchmark.

CC: @TomAFrench