chore: replace to_radix directive with brillig

[TomAFrench]

Copies @guipublic's work from noir-lang/noir#6386 into this repository

[github-actions]

Changes to circuit sizes

Generated at commit: decf1d87bac064a26b2338f328d9026e1d24c5b3, compared to commit: 9370c91dbc9c7b8eb38236e2fa3637e92d7f3786

🧾 Summary (100% most significant diffs)

Program	ACIR opcodes (+/-)	%	Circuit size (+/-)	%
private_kernel_empty	0 ➖	0.00%	+41,200 ❌	+4.57%
parity_root	0 ➖	0.00%	+164,800 ❌	+4.53%
rollup_block_root	0 ➖	0.00%	+123,600 ❌	+4.51%
rollup_merge	0 ➖	0.00%	+82,400 ❌	+4.51%
rollup_root	0 ➖	0.00%	+82,400 ❌	+4.43%
rollup_block_merge	0 ➖	0.00%	+82,400 ❌	+4.43%
rollup_base_private	0 ➖	0.00%	+41,201 ❌	+1.21%
rollup_base_public	0 ➖	0.00%	+41,200 ❌	+1.10%

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Full diff report 👇

Program	ACIR opcodes (+/-)	%	Circuit size (+/-)	%
private_kernel_empty	612 (0)	0.00%	942,839 (+41,200)	+4.57%
parity_root	5,034 (0)	0.00%	3,801,552 (+164,800)	+4.53%
rollup_block_root	4,489 (0)	0.00%	2,863,252 (+123,600)	+4.51%
rollup_merge	3,419 (0)	0.00%	1,909,446 (+82,400)	+4.51%
rollup_root	11,989 (0)	0.00%	1,940,906 (+82,400)	+4.43%
rollup_block_merge	12,005 (0)	0.00%	1,940,920 (+82,400)	+4.43%
rollup_base_private	335,062 (0)	0.00%	3,450,602 (+41,201)	+1.21%
rollup_base_public	472,329 (0)	0.00%	3,786,954 (+41,200)	+1.10%