SFCGAL ST_AlphaShape and ST_OptimalAlphaShape

[robe]

This will provide the CGAL ST_AlphaShape and ST_OptimalAlphaShape function exposed via SFCGAL. This requires SFCGAL ≥ 1.4.1 to be enabled.

Associated pull request:

​https://git.osgeo.org/gitea/postgis/postgis/pulls/98

[Regina Obe <lr@…>]

In a341034/git:

Closes ​https://git.osgeo.org/gitea/postgis/postgis/pulls/98
Closes #5143
Squashed commit of the following:

commit 6dad8a00b11e5961c08ebc676f10bfbf25c8eff1
Author: Regina Obe <lr@…>
Date: Tue May 3 18:35:28 2022 -0400

Change tests to check for sfcgal version at compile time
Fix docs, function signature and xml validaty

commit 4ba5288a7dece6cb14a204c1206345c7cc9f491a
Author: Loïc Bartoletti <loic.bartoletti@…>
Date: Tue May 3 06:47:07 2022 +0200

fix tests

commit 88b449750e6c5152741c16659771136747253ff8
Author: Loïc Bartoletti <loic.bartoletti@…>
Date: Tue May 3 06:32:26 2022 +0200

fix if postgis_sfcgal_version and fix build

commit 6865e31dd9f078dd0e05a72efc3282c613b97fc9
Author: Loïc Bartoletti <loic.bartoletti@…>
Date: Tue May 3 06:18:22 2022 +0200

seperate alphashape test

commit cefccb67156b4fc7d797a6ff199c76b2e8a74754
Author: Loïc Bartoletti <loic.bartoletti@…>
Date: Tue May 3 05:58:57 2022 +0200

fix the ifdef part and add a message error

commit eb3801e92aa48f42edaa828f3f0fced44b118f32
Author: Loïc Bartoletti <loic.bartoletti@…>
Date: Tue May 3 05:58:29 2022 +0200

add informaiton aoubt SFCGAL > 1.4.1

commit e96550d4d89f7b8ddb4e09c7bd7845a37f3f7bb5
Author: Loïc Bartoletti <loic.bartoletti@…>
Date: Mon May 2 10:40:09 2022 +0200

fix doc

commit 0b5e6a35b317b285b133ff8247c761da0e40d83e
Author: Loïc Bartoletti <loic.bartoletti@…>
Date: Mon May 2 09:44:49 2022 +0200

Use singular: AlphaShapes ⇒ AlphaShape

commit 8e92c13cc0bb72760d467b35b4f4a409732bfb17
Author: Loïc Bartoletti <loic.bartoletti@…>
Date: Fri Mar 4 11:55:21 2022 +0100

Add SFCGAL optimal alpha shapes doc

commit 734c430d337354143b1fe466f6e8bf1597c6e674
Author: Loïc Bartoletti <loic.bartoletti@…>
Date: Fri Mar 4 11:33:16 2022 +0100

Add SFCGAL alpha shapes

[Regina Obe <lr@…>]

In 82538c6/git:

References ​https://git.osgeo.org/gitea/postgis/postgis/pulls/98
References #5143
Add build image step of Alpha shapes to image builder
Update pots and pos to include new AlphaShape additions and references