tpl/collections: Speed up where and sort performance

tpl/collections: Speed up where and sort performance

```bash
goos: darwin
goarch: arm64
pkg: github.com/gohugoio/hugo/tpl/collections
cpu: Apple M1 Pro
                                        │ master.bench │       fix-whereperfalloc.bench       │
                                        │    sec/op    │   sec/op     vs base                 │
WhereOps/eq-10                            139.62µ ± 3%   66.04µ ± 2%  -52.70% (p=0.002 n=6)
WhereOps/ne-10                            139.54µ ± 1%   65.68µ ± 2%  -52.93% (p=0.002 n=6)
WhereOps/like-10                           179.8µ ± 3%   106.7µ ± 1%  -40.66% (p=0.002 n=6)
WhereSliceOfStructPointersWithMethod-10    350.7µ ± 1%   252.2µ ± 2%  -28.09% (p=0.002 n=6)
WhereAndSortPages/Where-10                120.93µ ± 1%   81.69µ ± 1%  -32.45% (p=0.002 n=6)
WhereAndSortPages/Sort-10                  1.608m ± 1%   1.165m ± 1%  -27.52% (p=0.002 n=6)
geomean                                    117.2µ        149.4µ       -40.03%               ¹

                                        │ master.bench  │       fix-whereperfalloc.bench        │
                                        │     B/op      │     B/op      vs base                 │
WhereOps/eq-10                             52.18Ki ± 0%   36.62Ki ± 0%  -29.82% (p=0.002 n=6)
WhereOps/ne-10                             52.18Ki ± 0%   36.62Ki ± 0%  -29.82% (p=0.002 n=6)
WhereOps/like-10                           52.20Ki ± 0%   36.63Ki ± 0%  -29.83% (p=0.002 n=6)
WhereSliceOfStructPointersWithMethod-10    64.52Ki ± 0%   64.59Ki ± 0%   +0.12% (p=0.002 n=6)
WhereAndSortPages/Where-10                 21.05Ki ± 0%   21.11Ki ± 0%   +0.30% (p=0.002 n=6)
WhereAndSortPages/Sort-10                 591.15Ki ± 0%   51.82Ki ± 0%  -91.23% (p=0.002 n=6)
geomean                                    7.690Ki        38.91Ki       -44.13%               ¹

                                        │ master.bench │       fix-whereperfalloc.bench       │
                                        │  allocs/op   │  allocs/op   vs base                 │
WhereOps/eq-10                             2.515k ± 0%   1.517k ± 0%  -39.68% (p=0.002 n=6)
WhereOps/ne-10                             2.515k ± 0%   1.517k ± 0%  -39.68% (p=0.002 n=6)
WhereOps/like-10                           2.515k ± 0%   1.517k ± 0%  -39.68% (p=0.002 n=6)
WhereSliceOfStructPointersWithMethod-10    4.503k ± 0%   4.504k ± 0%   +0.02% (p=0.002 n=6)
WhereAndSortPages/Where-10                 1.029k ± 0%   1.030k ± 0%   +0.10% (p=0.002 n=6)
WhereAndSortPages/Sort-10                 20.736k ± 0%   1.012k ± 0%  -95.12% (p=0.002 n=6)
geomean                                     358.5        1.594k       -53.04%               ¹
```