Introduce Replace [and Find] in find protocol

Previously there was a single replace action and the options would indicate if it was a “replace all”, this mimics the “find” (which can be a “find all”) but since single match replacement is somewhat different than a “replace all”, as the former may need to know the captures from a previous find action, it makes sense to factor out these things as different actions.
Simplify implementation of OakTextViewFindServer
Implement Replace [and Find] bound to ⌥⌘G

Currently this is implemented in OakTextView which means that it doesn’t work for macros. Some refactoring is in order so that the implementation can be shared (lack of sharing has to do with how OakTextView reports status to Find dialog or via tool tips, and macros want none of that).

There is also no check to see if the current state of the editor is the result of a find operation, i.e. you can invoke “replace” regardless of wether or not “find” was the last action.

Finally, doing a multi-file search and using “find next” at the end of one document, which brings you to the first match of next document (part of the results), will not update “captures” from a potential regular expression search, meaning that if you then do “replace”, and your replacement string is a format string that references the match (via $1-n) then it will not be correctly expanded.

Closes #104.