This commit adds the ability to change directories using the compiler's
internal filesystem abstraction. This is a prerequisite for writing tests
which are sensitive to the current working directory.
In addition to supporting the `chdir()` operation, this commit also fixes
`getDefaultLibLocation()` for mock filesystems to not assume `node_modules`
is in the current directory, but to resolve it similarly to how Node does
by progressively looking higher in the directory tree.
PR Close#33828
51720745dd