Construct arg vector manually rather than parse string

By constructing an arg vector manually, we no longer need to quote arguments

Mandate that args must be passed when building a command

Now you need to provide an args array when building a command.
There are a handful of places where we need to deal with a string,
such as with user-defined custom commands, and for those we now require
that at the callsite they use str.ToArgv to do that. I don't want
to provide a method out of the box for it because I want to discourage its
use.

For some reason we were invoking a command through a shell when amending a
commit, and I don't believe we needed to do that as there was nothing user-
supplied about the command. So I've switched to using a regular command out-
side the shell there

pkg/integration/components/test.go

@@ -22,7 +22,7 @@ const unitTestDescription = "test test"
 type IntegrationTest struct {
 	name         string
 	description  string
-	extraCmdArgs string
+	extraCmdArgs []string
 	skip         bool
 	setupRepo    func(shell *Shell)
 	setupConfig  func(config *config.AppConfig)
@@ -45,7 +45,7 @@ type NewIntegrationTestArgs struct {
 	// runs the test
 	Run func(t *TestDriver, keys config.KeybindingConfig)
 	// additional args passed to lazygit
-	ExtraCmdArgs string
+	ExtraCmdArgs []string
 	// for when a test is flakey
 	Skip bool
 	// to run a test only on certain git versions
@@ -128,7 +128,7 @@ func (self *IntegrationTest) Description() string {
 	return self.description
 }
 
-func (self *IntegrationTest) ExtraCmdArgs() string {
+func (self *IntegrationTest) ExtraCmdArgs() []string {
 	return self.extraCmdArgs
 }