Add ability to start an interactive rebase onto an appropriate base

A common issue I have is that I want to move a commit from the top of my branch
all the way down to the first commit on the branch. To do that, I need to navigate
down to the first commit on my branch, press 'e' to start an interactive rebase,
then navigate back up to the top of the branch, then move my commit back down to
the base. This is annoying.

Similarly annoying is moving the commit one-by-one without explicitly starting
an interactive rebase, because then each individual step is its own rebase which
takes a while in aggregate.

This PR allows you to press 'i' from the commits view to start an interactive
rebase from an 'appropriate' base. By appropriate, we mean that we want to start
from the HEAD and stop when we reach the first merge commit or commit on the main
branch. This may end up including more commits than you need, but it doesn't make
a difference.

docs/keybindings/Keybindings_en.md

@@ -79,6 +79,7 @@ _Legend: `<c-b>` means ctrl+b, `<a-b>` means alt+b, `B` means shift+b_
   <kbd>R</kbd>: Reword commit with editor
   <kbd>d</kbd>: Delete commit
   <kbd>e</kbd>: Edit commit
+  <kbd>i</kbd>: Start interactive rebase
   <kbd>p</kbd>: Pick commit (when mid-rebase)
   <kbd>F</kbd>: Create fixup commit for this commit
   <kbd>S</kbd>: Squash all 'fixup!' commits above selected commit (autosquash)

docs/keybindings/Keybindings_ja.md

@@ -98,6 +98,7 @@ _Legend: `<c-b>` means ctrl+b, `<a-b>` means alt+b, `B` means shift+b_
   <kbd>R</kbd>: エディタでコミットメッセージを編集
   <kbd>d</kbd>: コミットを削除
   <kbd>e</kbd>: コミットを編集
+  <kbd>i</kbd>: Start interactive rebase
   <kbd>p</kbd>: Pick commit (when mid-rebase)
   <kbd>F</kbd>: このコミットに対するfixupコミットを作成
   <kbd>S</kbd>: Squash all 'fixup!' commits above selected commit (autosquash)

docs/keybindings/Keybindings_ko.md

@@ -263,6 +263,7 @@ _Legend: `<c-b>` means ctrl+b, `<a-b>` means alt+b, `B` means shift+b_
   <kbd>R</kbd>: 에디터에서 커밋메시지 수정
   <kbd>d</kbd>: 커밋 삭제
   <kbd>e</kbd>: 커밋을 편집
+  <kbd>i</kbd>: Start interactive rebase
   <kbd>p</kbd>: Pick commit (when mid-rebase)
   <kbd>F</kbd>: Create fixup commit for this commit
   <kbd>S</kbd>: Squash all 'fixup!' commits above selected commit (autosquash)

docs/keybindings/Keybindings_nl.md

@@ -142,6 +142,7 @@ _Legend: `<c-b>` means ctrl+b, `<a-b>` means alt+b, `B` means shift+b_
   <kbd>R</kbd>: Hernoem commit met editor
   <kbd>d</kbd>: Verwijder commit
   <kbd>e</kbd>: Wijzig commit
+  <kbd>i</kbd>: Start interactive rebase
   <kbd>p</kbd>: Kies commit (wanneer midden in rebase)
   <kbd>F</kbd>: Creëer fixup commit
   <kbd>S</kbd>: Squash bovenstaande commits

docs/keybindings/Keybindings_pl.md

@@ -63,6 +63,7 @@ _Legend: `<c-b>` means ctrl+b, `<a-b>` means alt+b, `B` means shift+b_
   <kbd>R</kbd>: Zmień nazwę commita w edytorze
   <kbd>d</kbd>: Usuń commit
   <kbd>e</kbd>: Edytuj commit
+  <kbd>i</kbd>: Start interactive rebase
   <kbd>p</kbd>: Wybierz commit (podczas zmiany bazy)
   <kbd>F</kbd>: Utwórz commit naprawczy dla tego commita
   <kbd>S</kbd>: Spłaszcz wszystkie commity naprawcze powyżej zaznaczonych commitów (autosquash)

docs/keybindings/Keybindings_ru.md

@@ -146,6 +146,7 @@ _Связки клавиш_
   <kbd>R</kbd>: Переписать коммит с помощью редактора
   <kbd>d</kbd>: Удалить коммит
   <kbd>e</kbd>: Изменить коммит
+  <kbd>i</kbd>: Start interactive rebase
   <kbd>p</kbd>: Выбрать коммит (в середине перебазирования)
   <kbd>F</kbd>: Создать fixup коммит для этого коммита
   <kbd>S</kbd>: Объединить все 'fixup!' коммиты выше в выбранный коммит (автосохранение)

docs/keybindings/Keybindings_zh-CN.md

@@ -144,6 +144,7 @@ _Legend: `<c-b>` means ctrl+b, `<a-b>` means alt+b, `B` means shift+b_
   <kbd>R</kbd>: 使用编辑器重命名提交
   <kbd>d</kbd>: 删除提交
   <kbd>e</kbd>: 编辑提交
+  <kbd>i</kbd>: Start interactive rebase
   <kbd>p</kbd>: 选择提交（变基过程中）
   <kbd>F</kbd>: 创建修正提交
   <kbd>S</kbd>: 压缩在所选提交之上的所有“fixup!”提交（自动压缩）

docs/keybindings/Keybindings_zh-TW.md

@@ -187,6 +187,7 @@ _說明：`<c-b>` 表示 Ctrl+B、`<a-b>` 表示 Alt+B，`B`表示 Shift+B_
   <kbd>R</kbd>: 使用編輯器改寫提交
   <kbd>d</kbd>: 刪除提交
   <kbd>e</kbd>: 編輯提交
+  <kbd>i</kbd>: Start interactive rebase
   <kbd>p</kbd>: 挑選提交 (於變基過程中)
   <kbd>F</kbd>: 為此提交建立修復提交
   <kbd>S</kbd>: 壓縮上方所有的“fixup!”提交 (自動壓縮)