[MM-53968] Includes mattermost-plugin-api into the mono repo (#24235)

Include https://github.com/mattermost/mattermost-plugin-api into the mono repo

Co-authored-by: Jesse Hallam <jesse.hallam@gmail.com>
Co-authored-by: Michael Kochell <mjkochell@gmail.com>
Co-authored-by: Alejandro García Montoro <alejandro.garciamontoro@gmail.com>
Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>
Co-authored-by: Alex Dovenmuehle <alex.dovenmuehle@mattermost.com>
Co-authored-by: Michael Kochell <6913320+mickmister@users.noreply.github.com>
Co-authored-by: Christopher Poile <cpoile@gmail.com>
Co-authored-by: İlker Göktuğ Öztürk <ilkergoktugozturk@gmail.com>
Co-authored-by: Shota Gvinepadze <wineson@gmail.com>
Co-authored-by: Ali Farooq <ali.farooq0@pm.me>
Co-authored-by: Maria A Nunez <maria.nunez@mattermost.com>
Co-authored-by: Daniel Espino García <larkox@gmail.com>
Co-authored-by: Christopher Speller <crspeller@gmail.com>
Co-authored-by: Alex Dovenmuehle <adovenmuehle@gmail.com>
Co-authored-by: Szymon Gibała <szymongib@gmail.com>
Co-authored-by: Lev <1187448+levb@users.noreply.github.com>
Co-authored-by: Jason Frerich <jason.frerich@mattermost.com>
Co-authored-by: Agniva De Sarker <agnivade@yahoo.co.in>
Co-authored-by: Artur M. Wolff <artur.m.wolff@gmail.com>
Co-authored-by: Madhav Hugar <16546715+madhavhugar@users.noreply.github.com>
Co-authored-by: Joe <security.joe@pm.me>
Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>
Co-authored-by: José Peso <trilopin@users.noreply.github.com>

server/public/pluginapi/experimental/panel/store.go

@@ -0,0 +1,53 @@
+package panel
+
+import (
+	"errors"
+
+	"github.com/mattermost/mattermost/server/public/pluginapi"
+)
+
+type Store interface {
+	SetPanelPostID(userID string, postID string) error
+	GetPanelPostID(userID string) (string, error)
+	DeletePanelPostID(userID string) error
+}
+
+type panelStore struct {
+	kv        *pluginapi.KVService
+	keyPrefix string
+}
+
+func NewPanelStore(kv *pluginapi.KVService, keyPrefix string) Store {
+	return &panelStore{
+		kv:        kv,
+		keyPrefix: keyPrefix,
+	}
+}
+
+func (ps *panelStore) SetPanelPostID(userID, postID string) error {
+	ok, err := ps.kv.Set(ps.getKey(userID), postID)
+	if err != nil {
+		return err
+	}
+	if !ok {
+		return errors.New("value not set without errors")
+	}
+	return nil
+}
+
+func (ps *panelStore) GetPanelPostID(userID string) (string, error) {
+	var postID string
+	err := ps.kv.Get(ps.getKey(userID), &postID)
+	if err != nil {
+		return "", err
+	}
+	return postID, nil
+}
+
+func (ps *panelStore) DeletePanelPostID(userID string) error {
+	return ps.kv.Delete(ps.getKey(userID))
+}
+
+func (ps *panelStore) getKey(userID string) string {
+	return ps.keyPrefix + "-" + userID
+}