Project refactor, add anthropic API support

- Split pkg/cli/cmd.go into new pkg/cmd package
- Split pkg/cli/functions.go into pkg/lmcli/tools package
- Refactor pkg/cli/openai.go to pkg/lmcli/provider/openai

Other changes:

- Made models configurable
- Slight config reorganization

pkg/cmd/reply.go

@@ -0,0 +1,49 @@
+package cmd
+
+import (
+	"fmt"
+
+	cmdutil "git.mlow.ca/mlow/lmcli/pkg/cmd/util"
+	"git.mlow.ca/mlow/lmcli/pkg/lmcli"
+	"git.mlow.ca/mlow/lmcli/pkg/lmcli/model"
+	"github.com/spf13/cobra"
+)
+
+func ReplyCmd(ctx *lmcli.Context) *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "reply <conversation> [message]",
+		Short: "Reply to a conversation",
+		Long:  `Sends a reply to conversation and writes the response to stdout.`,
+		Args: func(cmd *cobra.Command, args []string) error {
+			argCount := 1
+			if err := cobra.MinimumNArgs(argCount)(cmd, args); err != nil {
+				return err
+			}
+			return nil
+		},
+		RunE: func(cmd *cobra.Command, args []string) error {
+			shortName := args[0]
+			conversation := cmdutil.LookupConversation(ctx, shortName)
+
+			reply := inputFromArgsOrEditor(args[1:], "# How would you like to reply?\n", "")
+			if reply == "" {
+				return fmt.Errorf("No reply was provided.")
+			}
+
+			cmdutil.HandleConversationReply(ctx, conversation, true, model.Message{
+				ConversationID:  conversation.ID,
+				Role:            model.MessageRoleUser,
+				Content: reply,
+			})
+			return nil
+		},
+		ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+			compMode := cobra.ShellCompDirectiveNoFileComp
+			if len(args) != 0 {
+				return nil, compMode
+			}
+			return ctx.Store.ConversationShortNameCompletions(toComplete), compMode
+		},
+	}
+	return cmd
+}