[fix-type-errors] Fix compilation errors when using unstable

[ebebbington]

Issue came about from @divy on discord.

Description

• Compilation errors when using Rhum and unstable. This is because unstable is proper unstable... even when passing the --unstable flag to something that doesn't need it, it will throw the below errors:

(Credit: @divy, discord)

[sno2]

The full error log is:

error: TS1371 [ERROR]: This import is never used as a value and must use 'import type' because the 'importsNotUsedAsValues' is set to 'error'.
import { MockServerRequestFn } from "./mocks/server_request.ts";
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    at https://deno.land/x/rhum@v1.1.2/src/interfaces.ts:1:1

TS1371 [ERROR]: This import is never used as a value and must use 'import type' because the 'importsNotUsedAsValues' is set to 'error'.
import { ITestPlan, ITestCase } from "./interfaces.ts";
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    at https://deno.land/x/rhum@v1.1.2/src/test_case.ts:2:1

TS1371 [ERROR]: This import is never used as a value and must use 'import type' because the 'importsNotUsedAsValues' is set to 'error'.
import { Mocked, Constructor } from "./types.ts";
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    at https://deno.land/x/rhum@v1.1.2/src/mock_builder.ts:1:1

TS1371 [ERROR]: This import is never used as a value and must use 'import type' because the 'importsNotUsedAsValues' is set to 'error'.
import {
^
    at https://deno.land/x/rhum@v1.1.2/mod.ts:4:1

TS1371 [ERROR]: This import is never used as a value and must use 'import type' because the 'importsNotUsedAsValues' is set to 'error'.
import {
^
    at https://deno.land/x/rhum@v1.1.2/mod.ts:8:1

TS1205 [ERROR]: Re-exporting a type when the '--isolatedModules' flag is provided requires using 'export type'.
export { Constructor, Stubbed } from "./src/types.ts";
         ~~~~~~~~~~~
    at https://deno.land/x/rhum@v1.1.2/mod.ts:14:10

TS1205 [ERROR]: Re-exporting a type when the '--isolatedModules' flag is provided requires using 'export type'.
export { Constructor, Stubbed } from "./src/types.ts";
                      ~~~~~~~
    at https://deno.land/x/rhum@v1.1.2/mod.ts:14:23

Found 7 errors.

from the following code:

import { Rhum } from "https://deno.land/x/rhum@v1.1.2/mod.ts";

Rhum.testPlan("my_file.ts", () => {
  Rhum.testSuite("suite1", () => {
    Rhum.testCase("test1", () => {
      Rhum.asserts.assertEquals(true, true);
    });
  });
});

Rhum.run();

when running deno run --unstable my_file.ts with Deno v1.4.0.