CI: add ASF-release support under macOS

This commit is used to make an ASF-release (tarball) file for committers
under macOS machine and enhance the developer experience for running the
script.

Main changes:
* Enforce GNU tar and sha512sum usage on macOS for generating artfacts
* Clean macOS extended attributes to prevent compilation errors on Linux
* Add platform and tool validation with installation guidance
* Support RC tag validation with base version matching in source
* Add interactive confirmations and enhanced verification steps
* Exclude release dir from .gitignore

Author: tuhaihe

.gitignore

@@ -45,7 +45,6 @@ config.status.lineno
 autom4te.cache
 configure.lineno
 Debug
-Release
 pgsql.sln
 cscope.*
 build.sh