feat: Add empty_array helper to create an array with all elements borrowed

[hsemenenko]

This PR adds a helper method to expose the new_all_borrowed op to create an array where all elements have been borrowed.

This is useful for array manipulation, for example combining two existing arrays without resorting to using array[Option[T], N] types.

[github-actions]

Bencher Report

Project	guppylang
Branch	hs/feat/create-array-all-taken
Testbed	Linux

Click to view all benchmark results

Benchmark	hugr_bytes	Benchmark Result bytes x 1e3 (Result Δ%)	Upper Boundary bytes x 1e3 (Limit %)	hugr_nodes	Benchmark Result nodes (Result Δ%)	Upper Boundary nodes (Limit %)
tests/benchmarks/test_big_array.py::test_big_array_compile	📈 view plot 🚷 view threshold	62.10 x 1e3 (0.00%) Baseline: 62.10 x 1e3	62.72 x 1e3 (99.01%)	📈 view plot 🚷 view threshold	4,585.00 (0.00%) Baseline: 4,585.00	4,630.85 (99.01%)
tests/benchmarks/test_ctrl_flow.py::test_many_ctrl_flow_compile	📈 view plot 🚷 view threshold	27.76 x 1e3 (0.00%) Baseline: 27.76 x 1e3	28.03 x 1e3 (99.01%)	📈 view plot 🚷 view threshold	1,301.00 (0.00%) Baseline: 1,301.00	1,314.01 (99.01%)
tests/benchmarks/test_queue_push_pop.py::test_queue_push_benchmark_compile	📈 view plot 🚷 view threshold	7.24 x 1e3 (0.00%) Baseline: 7.24 x 1e3	7.32 x 1e3 (99.01%)	📈 view plot 🚷 view threshold	310.00 (0.00%) Baseline: 310.00	313.10 (99.01%)
tests/benchmarks/test_queue_push_pop.py::test_queue_push_pop_benchmark_compile	📈 view plot 🚷 view threshold	9.86 x 1e3 (0.00%) Baseline: 9.86 x 1e3	9.96 x 1e3 (99.01%)	📈 view plot 🚷 view threshold	411.00 (0.00%) Baseline: 411.00	415.11 (99.01%)

🐰 View full continuous benchmarking report in Bencher

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.40%. Comparing base (58ad84b) to head (f74226f).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2327      +/-   ##
==========================================
+ Coverage   93.38%   93.40%   +0.02%     
==========================================
  Files         165      165              
  Lines       16248    16253       +5     
==========================================
+ Hits        15173    15181       +8     
+ Misses       1075     1072       -3     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[codspeed]

Merging this PR will not alter performance

✅ 11 untouched benchmarks

---

_{Comparing hs/feat/create-array-all-taken (f74226f) with main (58ad84b)}