v2.55.0: Verification Improvements and PostgreSQL 18 Support

Bug Fixes:

* Fix block incremental restore issue on non-default repository. (Reviewed by David Christensen, Aleksander Łukasz. Reported by Aleksander Łukasz.)
* Do not set recovery_target_timeline=current for PostgreSQL < 12. (Reviewed by Stefan Fercot.)
* Fix expire archive range logging. (Reviewed by Stefan Fercot. Reported by Aleš Zelený.)
* Fix error reporting for queries with no results. (Reviewed by Stefan Fercot. Reported by Susantha Bathige.)

Features:

* Verify recovery target timeline. (Reviewed by Stefan Fercot.)
* Allow verification of a specified backup. (Contributed by Maxim Michkov. Reviewed by David Steele.)
* Add support for S3/GCS requester pays. (Contributed by Timothée Peignier. Reviewed by David Steele.)
* PostgreSQL 18 experimental support. (Reviewed by Stefan Fercot.)
* Allow connections to PostgreSQL on abstract domain sockets. (Reviewed by Chris Bandy. Suggested by Chris Bandy.)
* Add numeric output to version command. (Contributed by Stefan Fercot. Reviewed by David Steele.)

Improvements:

* Allow backup command to operate on remote repositories. (Reviewed by Stefan Fercot.)
* Use lz4 for protocol compression. (Reviewed by Stefan Fercot.)
* Calculate content-md5 on S3 only when required. (Reviewed by David Christensen.)
* Warn when a value for a multi-key option is overwritten. (Reviewed by David Christensen, Stefan Fercot.)
* Add detail logging for expired archive path. (Contributed by Stefan Fercot. Reviewed by David Steele.)
* Remove support for PostgreSQL 9.4. (Reviewed by Stefan Fercot.)
* Remove autoconf/make build. (Reviewed by David Christensen.)

Documentation Improvements:

* Fix documentation for specifying multiple stanzas with tls-server-auth. (Reviewed by David Christensen, Stefan Fercot. Suggested by Terry MacAndrew.)
* Clarify incremental backup expiration. (Reviewed by Stefan Fercot.)
* Clarify requirement for local/remote pgBackRest versions to match. (Contributed by Greg Clough. Reviewed by David Steele.)
* Add FAQ about exporting self-contained cluster. (Contributed by Stefan Fercot. Reviewed by David Steele.)
* Caveat --tablespace-map-all regarding tablespace creation. (Reviewed by Stefan Fercot, Christophe Courtois. Suggested by Christophe Courtois.)
* Clarify behavior of --repo-retention-full-type. (Reviewed by Antoine Beaupré. Suggested by Antoine Beaupré.)
* Change --process-max recommendation for object stores to --repo-bundle. (Reviewed by Stefan Fercot.)
* Update unix_socket_directory to unix_socket_directories. (Contributed by hyunkyu han. Reviewed by David Steele.)
* Recommend not placing spool-path within pg_xlog/pg_wal. (Reviewed by Martín Marqués, Don Seiler. Suggested by Martín Marqués.)

test/code-count/file-type.yaml

@@ -1155,11 +1155,15 @@ src/command/restore/restore.c:
   class: core
   type: c
 
+src/command/restore/restore.h:
+  class: core
+  type: c/h
+
 src/command/restore/timeline.c:
   class: core
   type: c
 
-src/command/restore/restore.h:
+src/command/restore/timeline.h:
   class: core
   type: c/h
 
@@ -1263,6 +1267,14 @@ src/common/compress/bz2/decompress.h:
   class: core
   type: c/h
 
+src/common/compress/common.c:
+  class: core
+  type: c
+
+src/common/compress/common.h:
+  class: core
+  type: c/h
+
 src/common/compress/gz/common.c:
   class: core
   type: c
@@ -2607,6 +2619,14 @@ test/src/command/test/define.h:
   class: test/harness
   type: c/h
 
+test/src/command/test/lint.c:
+  class: test/harness
+  type: c
+
+test/src/command/test/lint.h:
+  class: test/harness
+  type: c/h
+
 test/src/command/test/test.c:
   class: test/harness
   type: c
@@ -2775,6 +2795,10 @@ test/src/common/harnessPostgres/harness170.c:
   class: test/harness
   type: c
 
+test/src/common/harnessPostgres/harness180.c:
+  class: test/harness
+  type: c
+
 test/src/common/harnessPostgres/harnessVersion.intern.h:
   class: test/harness
   type: c/h