gnucash: update to 5.3, enable SQL support + add libdbi packages

[cinerea0]

Testing the changes

• I tested the changes in this PR: YES

New package

• These new packages conform to the package requirements: YES

Local build testing

• I built this PR locally for my native architecture, x86_64-glibc (crossbuilds disabled for gnucash)

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cc: @manfredu

[cinerea0]

A few things I wanted to point out:

• gnucash's changelog is hosted on GitHub along with a mirror of its source code. That repo also hosts the same release tarballs that are hosted on SourceForge, so the distfiles could be set to that instead if we wanted to move away from SourceForge.
• The reason I split libdbi and libdbi-drivers as much as I did is because the docs subpackages are larger and have far more files than the base packages, and they contain information only relevant to developers.
• I added libdbi-drivers as a dependency to gnucash because, while it isn't required for basic functionality, you can't use the SQL backends without it.

[sgn]

I think it's better to split those 3 files into 3 packages:

/usr/lib/dbd/libdbdmysql.so
/usr/lib/dbd/libdbdpgsql.so
/usr/lib/dbd/libdbdsqlite3.so

Those files isn't that big itself, but I guess they will pull libmariaclient and libpgsql in which is big (I guess).

[cinerea0]

I think it's better to split those 3 files into 3 packages

In addition to or instead of the current splits?

[sgn]

I think it's better to split those 3 files into 3 packages

In addition to or instead of the current splits?

In addition to current split.

[cinerea0]

Moving each library out into its own package results in the main package being empty. Taking the trick from mpg123-extras and installing the readme as documentation doesn't work because all of the documentation is moved into libdbi-drivers-doc. Is there an another workaround?

[sgn]

build_style=meta, I would say, or let sqlite3, which is the lite version stay in main package.