Fix issue here source directive was not getting mapped to the correct types after multiple transformations

[uzair-inamdar]

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Description

The @source directives are added to the schema before schema transformations. Hence, need to be remapped after possible renames, replacements, and type merging. This was not happening with the existing code causing the @source directives to point to type names that either no longer existed (due to rename merges) or were pointing to the wrong type (type replacement transforms).

This fix introduces changes to the field mapper that happens after transformations, and make sure to map the @source directives to the correct or existing types.

Fixes #7771

Type of change

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• Bug fix (non-breaking change which fixes an issue)

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• [ x] Ran the solution on local machine to verify it fixed issues where issues were manifesting themselves before.

Test Environment:

• OS: MacOS Sonoma
• @graphql-mesh/1.1.0:
• NodeJS: 20.12

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