pgsql: Rename some functions to mention Relation instead of RelFileLoca

Rename some functions to mention Relation instead of RelFileLocator.

This is definitely shorter, and hopefully clearer.

Kyotaro Horiguchi, reviewed by Dilip Kumar and by me

Discussion: http://postgr.es/m/20220707.174436.1885393789789795413.horikyota.ntt@gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/09c5acee8ef90a9a94993dad937bdcd56ccaf1e3

Modified Files
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src/backend/storage/buffer/bufmgr.c   | 63 +++++++++++++++++------------------
src/backend/storage/buffer/localbuf.c | 16 ++++-----
src/backend/storage/smgr/smgr.c       |  4 +--
src/include/storage/buf_internals.h   |  7 ++--
src/include/storage/bufmgr.h          | 10 +++---
5 files changed, 50 insertions(+), 50 deletions(-)