[graph] Bug fixes in layer realizations

[graph] Bug fixes in layer realizations

Add bug fixes for layer realizations for making the graph
Many scenarios were missed about creating connections for the graph
which this patch fixes.

Further, this patch reduce the isCompilable() checks as the first
layer cant be determined till the topologicalSort() of the graph is done.
Added checkCompiledGraph() where first layer and some more checks like
types are checked.

See Also #986

**Self evaluation:**
1. Build test: [x]Passed [ ]Failed [ ]Skipped
2. Run test: [x]Passed [ ]Failed [ ]Skipped

Signed-off-by: Parichay Kapoor <pk.kapoor@samsung.com>