GHC 8.8 tracking ticket

This ticket summarizes what needs to do be done before the 8.8.1-alpha2 release.

• Backport #16603 (closed)
• !998 (merged)
• Core libraries (see #16690 (closed))
• #16517 (closed) (backport MR: !1155 (closed))
• Backport #16449 (closed) (!1021 (closed)) (backport MR: !1051 (merged))
• Backport !706 (closed) (backport MR: !1153 (merged))
• Merge !940 (merged)
• Backport !736 (closed) (merged with 0b91a029)
• Backport !1063 (closed) (#16312 (closed))
• Backport !869 (closed) (#16608 (closed)) (backport MR: !1239 (closed))
• Backport !769 (closed) (backport MR: !1154 (merged))
• Backport !1055 (closed) (#16066 (closed)) (backport MR: !1078 (merged))