feat(ir): more flexible dereferencing support for join right hand side

[kszucs]

Enables to use fields from parent tables of the join right hand side instead of enforcing to use the same exact table:

t1 = ibis.table(name="t1", schema={"a": "int64", "b": "string"})
t2 = ibis.table(name="t2", schema={"c": "int64", "d": "string"})

t3 = t2.mutate(e=t2.c + 1)
joined = t1.join(t3, [t1.a == t2.c])  # here we use t2.c instead of t3.c

Identify ambiguous cases and raise an error, like the following case:

t.join(t, [t.a == t.a])

depends on:

• feat(ir): support pretty printing arbitrary traversable objects #9043
• feat(common): also traverse nodes used as dictionary keys #9041

fixes #8581

[cpcloud]

LGTM mostly, just a few small requests.

Would really like to see a docstring for DerefMap but I won't block on that.