Change type of `rp` (range parent) in content script to not `any`

[melink14]

When I was originally fixing the code enough to enable type checking, it was too hard to fix the type of rp since it had too many different overloaded uses. I added a disable comment but ideally we should fix the type by making new well typed variables on demand instead of reusing rp

rikaikun/extension/rikaicontent.ts

Line 1074 in 72063a5

// eslint-disable-next-line @typescript-eslint/no-explicit-any