feat(xrpl): add contains flag utility

[kpitapeersyst]

feat(xrpl): add contains flag utility

Description

This PR aims to create a new utility package flag and use it across the existing transaction and ledger-entry-types to check bitwise flags in a consistent and reusable way.

Type of change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Refactoring

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code where needed
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective
• New and existing unit tests pass locally with my changes

Changes

xrpl

• Added xrpl/flag package with a Contains(currentFlag, flag uint32) bool utility function that checks if a flag is fully set within a combined flag value.
• Exported all flag constants across transaction and ledger-entry-types packages (e.g. asfRequireDest → AsfRequireDest) so they can be used externally with flag.Contains.
• Refactored all flag checks across transaction and ledger-entry-types packages to use flag.Contains.
• Added documentation for the flag package.

Notes

My first thought was to use currentFlag & flag != 0, which returns true if any bit overlaps between the two flags. This would have worked fine in most cases since flags are usually single-bit, but it breaks down for multi-bit flags where only a subset of bits match. For a function named Contains, the correct semantic is that all bits of the flag must be present, so I went with (currentFlag & flag) == flag instead. A flag != 0 guard was also added since without it, (x & 0) == 0 would always be true, silently making zero flags pass the check.

[GuillemGarciaDev]

Nice PR, just a small change!

[GuillemGarciaDev]

Just a little change