[php2cpg] fix annotation name and fullName

[TNSelahle]

• Fix the name and fullName properties of annotations

fixes https://harness.atlassian.net/browse/QT-921

Annotation(
    argumentIndex = -1,
    argumentLabel = None,
    argumentName = None,
    code = """PhpMcp\Server\Attributes\McpTool""",
    columnNumber = None,
    depthFirstOrder = -1,
    fullName = """PhpMcp\Server\Attributes\McpTool""",
    internalFlags = 0,
    lineNumber = Some(value = 26),
    name = "McpTool",
    offset = None,
    offsetEnd = None,
    order = 8
  )

[maltek]

use the character split to avoid a regex here (I wish there was a builtin takeRightWhile to avoid the array allocation as well):

Suggested change

	val name = fullName.split("\\\\").last
	val name = fullName.split('\\').last

[TNSelahle]

Thanks!