Fix DeadDataFlowElimination removing neccessary typehint

[Luo-Yihang]

Motivation

This is pr tries to fix the issue #1150, which suggests DeadDataFlowElimination may unintentionally remove the required type hint of a tasklet variable, leading to the failure of sdfg compilation.

Modification

Added the type hint expression to the beginning of the tasklet.

May need confirm

• Will it be better to add the type hint only if the variable is found in the tasklet code?
• Is it correct that the type hint is hardcoded to dace.float64? If not, what is the appropriate way to obtain the variable type?

[tbennun]

@Luo-Yihang the type hint should not be hardcoded to float64. You can get the type of the connector by first querying it (connectors are dictionaries), and if it's None you need to infer it from the memlet (which data container is connected to it).

It would be nice to not do it if the connector name is not found in the tasklet (see ASTFindReplace)

[tbennun]

Superseded by #1499