Make timestamp programmatically accessible

[Fabian Lupa]

Hi,

would it be possible to add a constant to the marker interface (for abapGit)? Doing READ REPORT on a 100k+ lines report to parse one line of comments is quite the performance killer ;)

For example:

INTERFACE lif_abapmerge_marker.
* abapmerge 0.14.8 - 2023-01-09T17:14:22.870Z
  CONSTANTS merge_timestamp TYPE string VALUE `2023-01-09T17:14:22.870Z`.
ENDINTERFACE.

[Lars Hvam]

yea, pull request welcome