Expose SelectedCommit to custom commands, deprecate Selected{Local,Reflog,Sub}Commit

SelectedCommit is context-dependent and points to SelectedLocalCommit,
SelectedReflogCommit, or SelectedSubCommit depending on which panel is active.

If none of these panels is active, it returns the selected local commit, which
is probably the most useful default (e.g. when defining custom commands for the
Files panel).

pkg/integration/tests/custom_commands/selected_commit.go

@@ -0,0 +1,67 @@
+package custom_commands
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var SelectedCommit = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Use the {{ .SelectedCommit }} template variable in different contexts",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupRepo: func(shell *Shell) {
+		shell.CreateNCommits(3)
+	},
+	SetupConfig: func(cfg *config.AppConfig) {
+		cfg.UserConfig.CustomCommands = []config.CustomCommand{
+			{
+				Key:     "X",
+				Context: "global",
+				Command: "printf '%s' '{{ .SelectedCommit.Name }}' > file.txt",
+			},
+		}
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		// Select different commits in each of the commit views
+		t.Views().Commits().Focus().
+			NavigateToLine(Contains("commit 01"))
+		t.Views().ReflogCommits().Focus().
+			NavigateToLine(Contains("commit 02"))
+		t.Views().Branches().Focus().
+			Lines(Contains("master").IsSelected()).
+			PressEnter()
+		t.Views().SubCommits().IsFocused().
+			NavigateToLine(Contains("commit 03"))
+
+		// SubCommits
+		t.GlobalPress("X")
+		t.FileSystem().FileContent("file.txt", Equals("commit 03"))
+
+		t.Views().SubCommits().PressEnter()
+		t.GlobalPress("X")
+		t.FileSystem().FileContent("file.txt", Equals("commit 03"))
+
+		// ReflogCommits
+		t.Views().ReflogCommits().Focus()
+		t.GlobalPress("X")
+		t.FileSystem().FileContent("file.txt", Equals("commit: commit 02"))
+
+		t.Views().ReflogCommits().PressEnter()
+		t.GlobalPress("X")
+		t.FileSystem().FileContent("file.txt", Equals("commit: commit 02"))
+
+		// LocalCommits
+		t.Views().Commits().Focus()
+		t.GlobalPress("X")
+		t.FileSystem().FileContent("file.txt", Equals("commit 01"))
+
+		t.Views().Commits().PressEnter()
+		t.GlobalPress("X")
+		t.FileSystem().FileContent("file.txt", Equals("commit 01"))
+
+		// None of these
+		t.Views().Files().Focus()
+		t.GlobalPress("X")
+		t.FileSystem().FileContent("file.txt", Equals("commit 01"))
+	},
+})