perf: prepare partial evaluation at boot for better performances

[davidebianchi]

This PR will improve performance of query generation of more than x20, and it seems also the allow and response.

Here the before/after on my machine:

Before:

BenchmarkEvaluateRequest-10                                 4534            255834 ns/op          194671 B/op       3024 allocs/op
BenchmarkEvaluateRequestWithQueryGeneration-10               154           7485473 ns/op         4507957 B/op     112217 allocs/op
BenchmarkEvaluateResponse-10                                1639            702470 ns/op          486613 B/op       7980 allocs/op

After:

BenchmarkEvaluateRequest-10                                 5054            208840 ns/op          165831 B/op       2437 allocs/op
BenchmarkEvaluateRequestWithQueryGeneration-10              3505            339451 ns/op          241816 B/op       4309 allocs/op
BenchmarkEvaluateResponse-10                                2014            576589 ns/op          418976 B/op       6992 allocs/op

[coveralls]

Pull Request Test Coverage Report for Build 11497740816

Details

• 98 of 105 (93.33%) changed or added relevant lines in 5 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.06%) to 85.013%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
sdk/evaluator.go	7	8	87.5%
core/input.go	5	7	71.43%
core/partialevaluators.go	34	38	89.47%

Files with Coverage Reduction	New Missed Lines	%
sdk/evaluator.go	1	82.89%

Totals
Change from base Build 11483635708:	-0.06%
Covered Lines:	2303
Relevant Lines:	2709

---

💛 - Coveralls

[fredmaggiowski]

LGTM