Remove circular dependencies

[jribbink]

Instructions

Remove circular dependencies that exist in flow-js-testing codebase. Some of the exported methods will need to be broken out into separate files in order to facilitate this.

Problem

When building via rollup the following circular dependencies appear

Circular dependency: src/file.js -> src/imports.js -> src/contract.js -> src/manager.js -> src/interaction.js -> src/file.js
Circular dependency: src/imports.js -> src/contract.js -> src/manager.js -> src/interaction.js -> src/imports.js
Circular dependency: src/manager.js -> src/interaction.js -> src/manager.js
Circular dependency: src/manager.js -> src/deploy-code.js -> src/manager.js
Circular dependency: src/file.js -> src/imports.js -> src/contract.js -> src/manager.js -> src/deploy-code.js -> src/file.js
Circular dependency: src/imports.js -> src/contract.js -> src/manager.js -> src/deploy-code.js -> src/imports.js
Circular dependency: src/file.js -> src/imports.js -> src/contract.js -> src/manager.js -> src/interaction.js -> src/file.js
Circular dependency: src/imports.js -> src/contract.js -> src/manager.js -> src/interaction.js -> src/imports.js
Circular dependency: src/manager.js -> src/interaction.js -> src/manager.js
Circular dependency: src/manager.js -> src/deploy-code.js -> src/manager.js
Circular dependency: src/file.js -> src/imports.js -> src/contract.js -> src/manager.js -> src/deploy-code.js -> src/file.js
Circular dependency: src/imports.js -> src/contract.js -> src/manager.js -> src/deploy-code.js -> src/imports.js

Steps to Reproduce

Attempt to build flow-js-testing

Acceptance Criteria

Rollup/microbundle does not show these warnings

Context

This is blocking #151 because the babel plugin for @onflow/fcl-bundle gets stuck in an infinite recursion due to this circular dependency tree.