Fix panic when double quoted strings are used for column names.

[krishvishal]

Now:

limbo> create table t (a,b,c); insert into t (a,b,c) values ("hello", 234, 432);
thread 'main' panicked at core/translate/expr.rs:1621:29:
internal error: entered unreachable code: Id should be resolved to a Column before translation
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

After fix:

limbo> create table t (a,b,c); insert into t (a,b,c) values ("hello", 234, 432);

  × Parse error: no such column: "hello" - should this be a string literal in single-quotes?

limbo>

Closes #800