Replace std::string with string

[rrsettgast]

This PR replaces instances of std::string with the string alias inside of GEOSX.

[TotoGaz]

You may be willing to remove the #include <string> too? There are still a bunch of them.

[rrsettgast]

You may be willing to remove the #include <string> too? There are still a bunch of them.

Oh. Yes.

[TotoGaz]

There are a couple of occurrences of std::to_string; don't know what to do with it though.

[sytuannguyen]

You may want to change also "const string" to "string const" as the rule said:

[TotoGaz]

Position of const is not restrained to string. It will probably be more efficient to deal with const position all at once, for all the argument types, in another PR, when we find/build an automated way to do this.

[rrsettgast]

Yes....we should do the const enforcement in a stand-alone PR.

[sytuannguyen]

Do you want to take also a look at the types: int and integer? Are they both related to the aliases localIndex/globalIndex?

[rrsettgast]

Do you want to take also a look at the types: int and integer? Are they both related to the aliases localIndex/globalIndex?

If they are actually a local or global index, then that they should be localIndex or globalIndex. Otherwise if they are an integer data type in the repository, they should be integer. If they are in a kernel, they should be int unless it is an index into an ArrayView.

Whatever the case...this PR is to fix string and only to fix string

[rrsettgast]

There are a couple of occurrences of std::to_string; don't know what to do with it though.

I think we keep them. If we ever change the string alias to something other than std::string we will have to make sure there is a UDC to std::string.