Add int64 `Tdim` support for `ExpandDims` (#14222)

* Add int64 `Tdim` support for `ExpandDims`

This fix tries to add int64 `Tdim` support for `ExpandDims`.
In `array_ops.cc`, `ExpandDims` registers both int32
and int64 support for `Tdim`. However, only int32 kernel
for `ExpandDims` has been supported.

This fix addresses the discrepancy by adding the support
of int64 `Tdim` for `ExpandDims`.

Additional tests has also been added to cover the changes.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Add test cases for int64 Tdim support for `ExpandDims`

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Sanitize .cc and .h file with clang-format -i --style=Google

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>