feat(git): Add bcommits_range picker (#2398)

* Filter bcommits by selection in visual mode

* Split bcommits_range into new picker

* Add option to run bcommits_range as operator

Starts operator-pending mode and shows commits in the range of lines
covered by the next text object or motion

* Rename range arguments to "first" and "last"

Can't use start/end, since end is an annoying keyword to use in lua
and start/stop doesn't fit as well

* Move operators functionality to new module

* Run bcommits if no range given to bcommits_range

* Make bcommits_range default to current line

Instead of calling bcommits

* Improve documentation of telescope.operators

* Add default value for last_operator

Default to a no-op callback

* Update bcommits_range for detached worktrees

See #2597

* Rename range arguments to "from" and "to"

* Move shared bcommits picker into single function

lua/telescope/operators.lua

@@ -0,0 +1,23 @@
+local operators = {}
+
+local last_operator = { callback = function(_) end, opts = {} }
+
+--- Execute the last saved operator callback and options
+operators.operator_callback = function()
+  last_operator.callback(last_operator.opts)
+end
+
+--- Enters operator-pending mode, then executes callback.
+--- See `:h map-operator`
+---
+---@param callback function: the function to call after exiting operator-pending
+---@param opts table: options to pass to the callback
+operators.run_operator = function(callback, opts)
+  last_operator = { callback = callback, opts = opts }
+  vim.o.operatorfunc = "v:lua.require'telescope.operators'.operator_callback"
+  -- feed g@ to enter operator-pending mode
+  -- 'i' required for which-key compatibility, etc.
+  vim.api.nvim_feedkeys("g@", "mi", false)
+end
+
+return operators