Support for representing cray pointers using OFP or FP (fixes #338)

[reuterbal]

The Cray pointer statement is understood by OFP and FParser but was not handled when translating the parse tree to Loki's IR. This adds functionality to represent these as Intrinsic nodes in the IR.

[github-actions[bot]]

Documentation for this branch can be viewed at https://sites.ecmwf.int/docs/loki/342/index.html

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 95.26%. Comparing base (a39336b) to head (aea722f).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #342 +/- ## ======================================= Coverage 95.25% 95.26% ======================================= Files 170 170 Lines 36258 36270 +12 ======================================= + Hits 34539 34551 +12 Misses 1719 1719 ``` | [Flag](https://app.codecov.io/gh/ecmwf-ifs/loki/pull/342/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ecmwf-ifs) | Coverage Δ | | |---|---|---| | [lint_rules](https://app.codecov.io/gh/ecmwf-ifs/loki/pull/342/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ecmwf-ifs) | `96.39% <ø> (ø)` | | | [loki](https://app.codecov.io/gh/ecmwf-ifs/loki/pull/342/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ecmwf-ifs) | `95.24% <100.00%> (+<0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ecmwf-ifs#carryforward-flags-in-the-pull-request-comment) to find out more.

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