Ensure, that Tramp cache works over absolute file names

Ensure, that Tramp cache works over absolute file names

* lisp/net/tramp.el (tramp-skeleton-directory-files)
(tramp-skeleton-directory-files-and-attributes)
(tramp-skeleton-set-file-modes-times-uid-gid)
(tramp-handle-add-name-to-file, tramp-handle-file-exists-p)
(tramp-handle-file-readable-p, tramp-handle-file-writable-p):
* lisp/net/tramp-adb.el (tramp-adb-handle-file-executable-p)
(tramp-adb-handle-file-exists-p)
(tramp-adb-handle-file-readable-p)
(tramp-adb-handle-file-writable-p)
* lisp/net/tramp-gvfs.el (tramp-gvfs-info, tramp-gvfs-handle-delete-file)
(tramp-gvfs-get-directory-attributes)
(tramp-gvfs-get-root-attributes)
(tramp-gvfs-handle-file-executable-p):
* lisp/net/tramp-sh.el (tramp-sh-handle-make-symbolic-link)
(tramp-sh-handle-file-exists-p)
(tramp-sh-handle-set-visited-file-modtime)
(tramp-sh-handle-file-selinux-context)
(tramp-sh-handle-set-file-selinux-context)
(tramp-sh-handle-file-acl, tramp-sh-handle-file-executable-p)
(tramp-sh-handle-file-readable-p)
(tramp-sh-handle-file-directory-p)
(tramp-sh-handle-file-writable-p)
(tramp-sh-handle-file-ownership-preserved-p)
(tramp-sh-handle-add-name-to-file)
(tramp-sh-handle-copy-directory, tramp-sh-handle-delete-file)
(tramp-sh-handle-dired-compress-file):
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-handle-add-name-to-file)
(tramp-sudoedit-handle-delete-file)
(tramp-sudoedit-handle-file-acl)
(tramp-sudoedit-handle-file-executable-p)
(tramp-sudoedit-handle-file-exists-p)
(tramp-sudoedit-handle-file-readable-p)
(tramp-sudoedit-handle-file-selinux-context)
(tramp-sudoedit-handle-file-writable-p)
(tramp-sudoedit-handle-make-symbolic-link)
(tramp-sudoedit-handle-set-file-selinux-context):
Use `expand-file-name'.  (Bug#57572)

* lisp/net/tramp-cache.el (tramp-flush-file-function):
Expand `buffer-file-name'.  (Bug#57676)

* lisp/net/tramp.el (tramp-file-name-unify): Extend error message.

* lisp/net/tramp-sh.el (tramp-sh-handle-make-symbolic-link):
* lisp/net/tramp-smb.el (tramp-smb-handle-make-symbolic-link):
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-handle-make-symbolic-link):
Do not check remoteness of TARGET anymore.