SqlCMD variables are not handled by schema compare APIs

Type: Bug

1. Compare dacpac with database.
2. It fails because sqlcmd variables are not correctly translated.
There differences because [$(DB1)] is not Database1. [$(DB1)] has default value "Database1".

Extension version: 1.20.0
Azure Data Studio version: azuredatastudio 1.45.1 (88c21b1725a3e79440027bdb7b5a55fb036be0e2, 2023-08-03T00:42:37.945Z)
OS version: Windows_NT x64 10.0.20348
Restricted Mode: No
Preview Features: Disabled
Modes:

Start by reproducing the schema comparison described: compare a dacpac with a database that uses the SqlCMD variable $(DB1), whose default value is "Database1". Trace the schema compare APIs to find where the variable remains unresolved, and consider the issue done when the comparison translates it correctly without reporting a false difference.

Written by the indexing model from the issue text.