fix: TDS workflow consistency in Purchase Order (backport #42849)

[mergify]

• In Purchase Order and Purchase Invoice "Apply TDS" field "read_only" property based on Supplier Tax Withholding Category.
• While creating Purchase Invoice from Purchase Order if Tax withholding Category is set in Supplier than Tax withholding category will be copied from Purchase Order if it is set.
• Consistency in "Apply TDS" field "read_only" property on refresh.

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  This is an automatic backport of pull request fix: TDS workflow consistency in Purchase Order #42849 done by Mergify.