fixes default attributes for button_tag
fix accept nil options
fix button tag without options
fix form button
fix indentations
fix content_or_options to be replaced by options and set to nil
cleanup and move extracted method right into the helper
rollback to private method
remove private method and rewrite into more precise notation
Add Enum type to postgresql adapter's oids to prevent unknown OID warnings.
Merge pull request #14255 from prikha/master

Fixes #14254 ActionView button_tag helper default options values issue.
Added missing changlog entry for #14255
Simplify handling of defaults/options in button_tag

There's no need to rely on Active Support's Hash#reverse_merge for
simple cases with default values, since we can just merge from the
default rather than reverse merge from the options.

This also avoids the creation of one extra hash object by moving to a
Hash#merge! call.
Use 1.9 style hash on docs [ci skip]
Merge pull request #13244 from kommen/pg_enum_type_map

Add Enum type to postgresql adapter's oids to prevent unknown OID warnings
Fix enum test unused variable warning.

Related - https://github.com/rails/rails/commit/5c55aafd38f45ac019573f98438ffdbdc8c580f9
Merge pull request #14273 from vipulnsward/fix-warning-13244

Fix enum test unused variable warning.
Inline block to fix indent [ci skip]