Allow REFRESH MATERIALIZED VIEW to refresh caggs

[erimatnor]

It is now possible to use REFRESH MATERIALIZED VIEW as an
alternative to refresh_continuous_aggregate when doing "infinite"
refreshes.

[cevian]

How does this interact with dropped data? It would be great if this refreshed everything /that hasn't been dropped/

[erimatnor]

Note that this (temporarily) redirects REFRESH MATERIALIZED VIEW to the new refresh procedure instead of blocking. This is to avoid breaking existing update scripts while still having the command do something useful as opposed to calling the old materializer.

[codecov]

Codecov Report

Merging #2391 into master will increase coverage by 0.40%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2391      +/-   ##
==========================================
+ Coverage   88.51%   88.92%   +0.40%     
==========================================
  Files         212      212              
  Lines       34924    34788     -136     
==========================================
+ Hits        30912    30934      +22     
+ Misses       4012     3854     -158     

Impacted Files	Coverage Δ
src/continuous_agg.c	89.31% <ø> (ø)
tsl/src/continuous_aggs/options.c	94.59% <ø> (+71.42%)	⬆️
src/process_utility.c	93.64% <100.00%> (+2.53%)	⬆️
tsl/src/continuous_aggs/create.c	96.93% <100.00%> (+0.33%)	⬆️
tsl/src/fdw/shippable.c	82.85% <0.00%> (-11.43%)	⬇️
src/loader/bgw_message_queue.c	84.51% <0.00%> (-2.59%)	⬇️

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