scripted-diff: batch-recase BanMan variables

Summary:
-BEGIN VERIFY SCRIPT-
sed -i "s/banMap/banmap/g" src/banman.h src/banman.cpp
sed -i "s/netAddr/net_addr/g" src/banman.h src/banman.cpp
sed -i "s/sinceUnixEpoch/since_unix_epoch/g" src/banman.h src/banman.cpp
sed -i "s/bantimeoffset/ban_time_offset/g" src/banman.h src/banman.cpp
sed -i "s/subNet/sub_net/g" src/banman.h src/banman.cpp
sed -i "s/banReason/ban_reason/g" src/banman.h src/banman.cpp
sed -i "s/notifyUI/notify_ui/g" src/banman.h src/banman.cpp
sed -i "s/banEntry/ban_entry/g" src/banman.h src/banman.cpp
sed -i "s/nStart/n_start/g" src/banman.h src/banman.cpp
-END VERIFY SCRIPT-

This is a partial backport of Core PR14605 : https://github.com/bitcoin/bitcoin/pull/14605/commits/18185b57c32d0a43afeca4c125b9352c692923e9

Depends on D4129

Test Plan:

make check

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D4130