feat(GuildMemberManager): add addRole and removeRole methods

#9108 djs

src/managers/GuildMemberManager.js

@@ -614,6 +614,38 @@ class GuildMemberManager extends CachedManager {
     });
   }
 
+  /**
+   * Adds a role to a member.
+   * @param {GuildMemberResolvable} user The user to add the role from
+   * @param {RoleResolvable} role The role to add
+   * @param {string} [reason] Reason for adding the role
+   * @returns {Promise<GuildMember|User|Snowflake>}
+   */
+  async addRole(user, role, reason) {
+    const userId = this.guild.members.resolveId(user);
+    const roleId = this.guild.roles.resolveId(role);
+
+    await this.client.api.guilds(this.guild.id).members(userId).roles(roleId).put({ reason });
+
+    return this.resolve(user) ?? this.client.users.resolve(user) ?? userId;
+  }
+
+  /**
+   * Removes a role from a member.
+   * @param {UserResolvable} user The user to remove the role from
+   * @param {RoleResolvable} role The role to remove
+   * @param {string} [reason] Reason for removing the role
+   * @returns {Promise<GuildMember|User|Snowflake>}
+   */
+  async removeRole(user, role, reason) {
+    const userId = this.guild.members.resolveId(user);
+    const roleId = this.guild.roles.resolveId(role);
+
+    await this.client.api.guilds(this.guild.id).members(userId).roles(roleId).delete({ reason });
+
+    return this.resolve(user) ?? this.client.users.resolve(user) ?? userId;
+  }
+
   _fetchMany({
     limit = 0,
     withPresences: presences = true,