chore: move cli/tests/ -> tests/ (#22369)

This looks like a massive PR, but it's only a move from cli/tests ->
tests, and updates of relative paths for files.

This is the first step towards aggregate all of the integration test
files under tests/, which will lead to a set of integration tests that
can run without the CLI binary being built.

While we could leave these tests under `cli`, it would require us to
keep a more complex directory structure for the various test runners. In
addition, we have a lot of complexity to ignore various test files in
the `cli` project itself (cargo publish exclusion rules, autotests =
false, etc).

And finally, the `tests/` folder will eventually house the `test_ffi`,
`test_napi` and other testing code, reducing the size of the root repo
directory.

For easier review, the extremely large and noisy "move" is in the first
commit (with no changes -- just a move), while the remainder of the
changes to actual files is in the second commit.

cli/tests/testdata/coverage/complex.ts

@@ -1,74 +0,0 @@
-// This entire interface should be completely ignored by the coverage tool.
-export interface Complex {
-  // These comments should be ignored.
-  foo: string;
-
-  // But this is a stub, so this isn't really documentation.
-  bar: string;
-
-  // Really all these are doing is padding the line count.
-  baz: string;
-}
-
-// Lets add some wide characters to ensure that the absolute byte offsets are
-// being matched properly.
-//
-// 패딩에 대한 더 많은 문자.
-function dependency(
-  foo: string,
-  bar: string,
-  baz: string,
-): Complex {
-  return {
-    foo,
-    bar,
-    baz,
-  };
-}
-
-// Again just more wide characters for padding.
-//
-// 良い対策のためにいくつかのユニコード文字を投げる。
-export function complex(
-  foo: string,
-  bar: string,
-  baz: string,
-): Complex {
-  return dependency(
-    foo,
-    bar,
-    baz,
-  );
-}
-
-// And yet again for good measure.
-// 更多用於填充的字元。
-export function unused(
-  foo: string,
-  bar: string,
-  baz: string,
-): Complex {
-  return complex(
-    foo,
-    bar,
-    baz,
-  );
-}
-
-// Using a non-ascii name again to ensure that the byte offsets match up
-// correctly.
-export const π = Math.PI;
-
-// And same applies for this one, this one is unused and will show up in
-// lacking coverage.
-export function ƒ(): number {
-  return (
-    0
-  );
-}
-
-// This arrow function should also show up as uncovered.
-console.log("%s", () => 1);
-
-// Make sure emojis work properly
-console.log("📣❓");