[chore] Text formatting overhaul (#1406)

* Implement goldmark debug print for hashtags and mentions

* Minify HTML in FromPlain

* Convert plaintext status parser to goldmark

* Move mention/tag/emoji finding logic into formatter

* Combine mention and hashtag boundary characters

* Normalize unicode when rendering hashtags

internal/text/goldmark_plaintext.go

@@ -0,0 +1,64 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2023 GoToSocial Authors admin@gotosocial.org
+
+   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 text
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
+)
+
+// plaintextParser implements goldmark.parser.BlockParser
+type plaintextParser struct {
+}
+
+var defaultPlaintextParser = &plaintextParser{}
+
+func newPlaintextParser() parser.BlockParser {
+	return defaultPlaintextParser
+}
+
+func (b *plaintextParser) Trigger() []byte {
+	return nil
+}
+
+func (b *plaintextParser) Open(parent ast.Node, reader text.Reader, pc parser.Context) (ast.Node, parser.State) {
+	_, segment := reader.PeekLine()
+	node := ast.NewParagraph()
+	node.Lines().Append(segment)
+	reader.Advance(segment.Len() - 1)
+	return node, parser.NoChildren
+}
+
+func (b *plaintextParser) Continue(node ast.Node, reader text.Reader, pc parser.Context) parser.State {
+	_, segment := reader.PeekLine()
+	node.Lines().Append(segment)
+	reader.Advance(segment.Len() - 1)
+	return parser.Continue | parser.NoChildren
+}
+
+func (b *plaintextParser) Close(node ast.Node, reader text.Reader, pc parser.Context) {}
+
+func (b *plaintextParser) CanInterruptParagraph() bool {
+	return false
+}
+
+func (b *plaintextParser) CanAcceptIndentedLine() bool {
+	return true
+}