getting_hired: rename lessons & place them in appropriate folders based on the website

[01zulfi]

Complete the following REQUIRED checkboxes:

• I have thoroughly read and understand The Odin Project Contributing Guide
• The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text

Complete the following checkboxes ONLY IF they are applicable to your PR. You can complete them later if they are not currently applicable:

• I have previewed all lesson files included in this PR with the Markdown preview tool to ensure the Markdown content is formatted correctly
• I have ensured all lesson files included in this PR follow the Layout Style Guide

---

1. Because:

Related to TheOdinProject/top-meta#109.

2. This PR:

1. Creates two folders called preparing_for_job_search and applying_and_interviewing.
2. Places lessons into the above folders based on their placement in each section on the getting hired course on the website.
3. Renames following lessons:
   1. introduction.md => how_this_course_will_work.md
   2. preparation.md => what_you_can_do_to_prepare.md
   3. preparing_to_interview.md => preparing_to_interview_and_interviewing.md

3. Additional Information:

n/a