core/vm: refactor memory resize

[MariusVanDerWijden]

Looks like (in some very EVM specific tests) we spent a lot of time resizing memory.
If the underlying array if big enough, we can speed it up a bit though:

goos: linux
goarch: amd64
pkg: github.com/ethereum/go-ethereum/core/vm
cpu: Intel(R) Core(TM) Ultra 7 155U
           │ /tmp/old.txt │              /tmp/new.txt              │
           │    sec/op    │    sec/op     vs base                  │
Resize-14     6.145n ± 9%   1.854n ± 14%  -69.83% (p=0.000 n=10)

           │ /tmp/old.txt │            /tmp/new.txt             │
           │     B/op     │    B/op     vs base                 │
Resize-14      5.000 ± 0%   5.000 ± 0%       ~ (p=1.000 n=10)

           │ /tmp/old.txt │             /tmp/new.txt              │
           │  allocs/op   │ allocs/op   vs base                   │
Resize-14    0.000 ± 0%     0.000 ± 0%       ~ (p=1.000 n=10) ¹

From the blocktest benchmark:

     620ms     10.93s (flat, cum)  9.92% of Total
         .          .     80:func (m *Memory) Resize(size uint64) {
      30ms       60ms     81:	if uint64(m.Len()) < size {
     590ms     10.87s     82:		m.store = append(m.store, make([]byte, size-uint64(m.Len()))...)
         .          .     83:	}
         .          .     84:}