* lisp/progmodes/ebrowse.el: Prefer hash-tables to obarrays

* lisp/progmodes/ebrowse.el: Prefer hash-tables to obarrays

Remove redundant :group args.
Use `defvar-local` and `setq-local` where possible.

(ebrowse-some): Use seq-some instead.
(ebrowse-every): Use seq-every-p instead.
(ebrowse-position): Use seq-position.
(ebrowse--tree-table): Rename from `ebrowse--tree-obarray`.
Change all users to use a hash-table rather than an obarray.
(ebrowse-for-all-trees): Adjust to the table being a hash-table.
(ebrowse-tree-table-as-alist): Rename from `ebrowse-tree-obarray-as-alist`.
(ebrowse-build-tree-obarray): Rename from `ebrowse-build-tree-obarray`.
(ebrowse-tree-mode): Remove redundant setting of `ebrowse--tree-obarray`.
(ebrowse-set-tree-indentation, ebrowse-view-file-other-frame)
(ebrowse-last-completion-table): Rename from
ebrowse-last-completion-obarray.
(ebrowse-position): Make it a proper struct.