v1.9.7-sc.1

This release contains a security fix, so update rather sooner than later!
Read the disclosure here: https://matrix.org/blog/2021/12/13/disclosure-buffer-overflow-in-libolm-and-matrix-js-sdk

Changelog:

• Freeform reactions (huge thanks to @tadzik for his PR on Element Web!)
• Some small fixes and improvements

• Upstream changes