Fix up memoize; bind to Python

[alexreinking]

Fixes #8777

[rtzam]

LGTM!

Compiler Segfaulting when using the added overload

[rtzam]

Here's a minimal python repro that segfaults at compilation time:

from halide import EvictionKey, Func, Var

x = Var("x")
f = Func("f")
f[x] = 0.0
f[x] = f[x] + 1

print("memoize scheduled")
f.memoize()
# f.memoize(EvictionKey(x))

print("JIT compiling...")
f.compile_jit()

print("realizing...")
result = f.realize([3])

print(result)

[rtzam]

Documenting slightly smaller test case demonstrating a different symptom:

from halide import Func, Var

x = Var("x")
f = Func("f")
f[x] = 0.0

print("memoize scheduled")
f.memoize()

print("JIT compiling...")
f.compile_jit()

print("realizing...")
result = f.realize([3])

print(result)

Which generates:

    f.compile_jit()
    ~~~~~~~~~~~~~^^
halide.halide_.HalideError: Error: Symbol not found: f.cache_miss

So the pure definition is also a bit broken as well as the update step

[alexreinking]

Failures, although many, are unrelated.