[feature] Support setting private notes on accounts (#1982)

* Support setting private notes on accounts

* Reformat comment whitespace

* Add missing license headers

* Use apiutil.ParseID

* Rename Note model and cache to AccountNote

* Update golden cache config in test/envparsing.sh

* Rename gtsmodel/note.go to gtsmodel/accountnote.go

* Update AccountNote uniqueness constraint name

Now has same prefix as other indexes on this table.

---------

Co-authored-by: tobi <31960611+tsmethurst@users.noreply.github.com>

internal/processing/account/note.go

@@ -0,0 +1,48 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package account
+
+import (
+	"context"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/id"
+)
+
+// PutNote updates the requesting account's private note on the target account.
+func (p *Processor) PutNote(ctx context.Context, requestingAccount *gtsmodel.Account, targetAccountID string, comment string) (*apimodel.Relationship, gtserror.WithCode) {
+	targetAccount, errWithCode := p.Get(ctx, requestingAccount, targetAccountID)
+	if errWithCode != nil {
+		return nil, errWithCode
+	}
+
+	note := &gtsmodel.AccountNote{
+		ID:              id.NewULID(),
+		AccountID:       requestingAccount.ID,
+		TargetAccountID: targetAccount.ID,
+		Comment:         comment,
+	}
+	err := p.state.DB.PutNote(ctx, note)
+	if err != nil {
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	return p.RelationshipGet(ctx, requestingAccount, targetAccount.ID)
+}