fix: Allow escaped double quotes in struct tag parser

[kankankanp]

• Do only one thing
• Non breaking API changes
• Tested

What did this pull request do?

This pull request adds support for escaping double quotes (" → ") in struct tag parsing.
Now you can write struct tags like gorm:"expression:to_tsvector('english', \"Name\")" and the parser will correctly interpret the escaped double quote.

This change addresses #7600.

User Case Description

When using PostgreSQL full text search, it is often necessary to refer to a column name with double quotes (e.g., "Name").
Previously, GORM's struct tag parser did not support writing double quotes inside the tag expression.
With this change, you can escape double quotes using a backslash, and the intended SQL expression will be parsed and used correctly.

Example:

type Object struct {
    Name string `gorm:"expression:to_tsvector('english', \"Name\")"`
}

This struct tag will now be correctly interpreted as:
to_tsvector('english', "Name")

[propel-code-bot]

Enable escaped double-quote handling in ParseTagSetting

Bug-fix PR that updates the struct tag parser to recognise and unescape the \" sequence so that users can embed literal double quotes inside gorm tags. The logic that glued backslash-escaped segments has been refactored for clarity, and an accompanying unit test demonstrates the new behaviour.

Key Changes

• Refactored loop in schema/utils.go to rebuild escaped segments using strings.HasSuffix instead of manual index juggling
• Added strings.ReplaceAll(val, ", ") to unescape double quotes for each setting value
• Introduced new test TestParseTagSettingWithDoubleQuoteEscape in schema/utils_test.go
• Removed obsolete variables and reduced code complexity within ParseTagSetting

Affected Areas

• schema/utils.go – function ParseTagSetting
• schema/utils_test.go – unit tests

This summary was automatically generated by @propel-code-bot

[kankankanp]

@jinzhu
If possible, I would be grateful if you could review this PR.