Restore maven build shortcut without adding a toolbar button

[Omega1001]

Reconnected the shortcut to an action that calls the previous code.
This is working without bringing the Button back, as Requested in #2048
Also closes #1618

Restores the previous behavior of the shortcut: (be reconnecting the old code)
If no maven launch configuration exists: Open the Create Dialog.
If exactly one configuration exists: Launch that configuration.
If more than one exists: Open a filterable/maneuverable Dialog to select which one you want.

@laeubi How's this?

[laeubi]

@Omega1001 many thanks for looking into this, you need to sign the ECA so we can accept your contribution, but as all tests pass already it seems working fine apart from that!

[github-actions]

Test Results

  324 files  ±0    324 suites  ±0   1h 14m 28s ⏱️ + 2m 32s
  692 tests ±0    669 ✅  - 1  21 💤 ±0  1 ❌ +1  1 🔥 ±0 
2 076 runs  ±0  2 011 ✅  - 1  63 💤 ±0  1 ❌ +1  1 🔥 ±0 

For more details on these failures and errors, see this check.

Results for commit 36daa83. ± Comparison against base commit 27eae6a.

[laeubi]

Other errors are unrelated!

[Omega1001]

@Omega1001 many thanks for looking into this, you need to sign the ECA so we can accept your contribution, but as all tests pass already it seems working fine apart from that!

Already did right after the push.
Github account is also linked.
Guess the update is a poll, so it should pick that up any time now.

[laeubi]

Looks fine to me, lets try!