Remove deprecated Clang-Format style options and improve readability

[anupsdf]

what

Remove deprecated clang-format20 style options and improve readability.

Note: BreakAfterReturnType: AllDefinitions is similar to the deprecated option we used to have before with AlwaysBreakAfterReturnType: AllDefinitions.

Example:

class A {
  int
  f() {
    return 0;
  };
};
int f();
int
f() {
  return 1;
}
int
LongName::AnotherLongName();

why

Keeping .clang-format config file up to date by removing deprecated options.

NOTE: Counter proposal in #5034

[Copilot]

Pull request overview

This PR removes deprecated clang-format style options that are no longer supported in clang-format 20 and updates the configuration file with their modern equivalents. The changes improve code formatting consistency by removing blank lines at the start of blocks, files, and functions throughout the codebase.

Key changes:

• Removed deprecated options: AlwaysBreakAfterReturnType, AlwaysBreakTemplateDeclarations, BreakBeforeInheritanceComma, BreakConstructorInitializersBeforeComma, BreakAfterJavaFieldAnnotations, ConstructorInitializerAllOnOneLineOrOnePerLine, KeepEmptyLinesAtTheStartOfBlocks, SpaceInEmptyParentheses, SpacesInCStyleCastParentheses, SpacesInParentheses
• Added modern equivalents: BreakAfterReturnType, BreakInheritanceList, BreakTemplateDeclarations, KeepEmptyLines, PackConstructorInitializers, SpacesInParens
• Updated C++ standard from Cpp11 to c++17
• Applied automatic formatting that removed empty lines at the start of blocks and files

Reviewed changes

Copilot reviewed 64 out of 64 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
.clang-format	Updated with clang-format 20 compatible options, replacing deprecated settings with modern equivalents
Multiple .cpp/.h files	Removed blank lines at the start of functions, blocks, and files as per new formatting rules
src/util/NonCopyable.h	Reformatted struct inheritance to multi-line format
src/rust/soroban/p25	Updated subproject commit reference
src/protocol-curr/xdr	Updated subproject commit reference