Preserve and display method body sequence points

[ImElio]

Link to issue(s) this pull request covers:

Problem

The CIL Method Body editor already loads PDB sequence point information, but this information was not visible in the instructions grid and could be lost during some edit/import flows.

This makes it harder to inspect how IL instructions map back to source lines when a matching PDB is available.

Solution

Preserve method body PDB information when copying CIL body options and preserve instruction sequence points when importing instructions.

This also adds a read-only "Sequence Point" column to the Method Body editor. The column shows the source file plus line/column range, and the tooltip shows the full source path when available. Hidden sequence points are displayed using the existing localized resource.

Tested with:

• dnSpy.AsmEditor net48 build
• dnSpy.AsmEditor net10.0-windows build
• Manual check using Newtonsoft.Json.dll with matching PDB