remove or refactor the MMR section

[jingyi-zhao-01]

Is your feature request related to a problem? Please describe.
the MMR section is quite outdated

• party MMR no longer exist
• solo MMR is outdated (looks like this is a backend problem)
• the date filter range is capped at 2017, not beyond
  Describe the solution you'd like
• remove party MMR
• be able to fetch up to date MMR
• modify the filter range so it caps to the current date
• some css enhancement

Describe alternatives you've considered

• remove MMR section from tab
  Teachability, Documentation, Adoption, Migration Strategy