Add T2 mapping with T2prep FLASH

[ckolbPTB]

No description provided.

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
/home/runner/.local/lib/python3.12/site-packages/mrseq
_version.py	7	7	0%	2–9
/home/runner/.local/lib/python3.12/site-packages/mrseq/preparations
t2_prep.py	51	1	98%	195
/home/runner/.local/lib/python3.12/site-packages/mrseq/scripts
radial_flash.py	140	11	92%	101, 104, 259, 345, 403–408, 428, 434
spiral_flash.py	119	10	92%	95, 230, 312, 362–367, 386, 392
t1_inv_rec_gre_single_line.py	93	9	90%	162, 255, 298–303, 330, 336
t1_inv_rec_se_single_line.py	106	9	92%	219, 316, 375–380, 407, 413
t1_molli_bssfp.py	141	13	91%	216, 282–284, 299, 374, 428–433, 454, 460
t1_t2_spiral_cmrf.py	148	12	92%	89, 95, 114, 167, 384, 431–436, 462, 468
t1rho_se_single_line.py	102	8	92%	310, 367–372, 399, 405
t2_multi_echo_se_single_line.py	96	9	91%	162, 261, 314–319, 344, 350
t2_t2prep_flash.py	143	15	90%	103, 226, 243, 277–279, 291, 367, 429–434, 454, 460
t2star_multi_echo_flash.py	145	14	90%	114, 233, 280–282, 294, 390, 452–457, 477, 483
/home/runner/.local/lib/python3.12/site-packages/mrseq/utils
ismrmrd.py	93	2	98%	173, 179
sequence_helper.py	59	4	93%	105, 133–134, 162
trajectory.py	149	3	98%	45, 87, 354
TOTAL	1723	127	93%

Tests	Skipped	Failures	Errors	Time
377	0 💤	0 ❌	0 🔥	1m 38s ⏱️

[schuenke]

LGTM

@ckolbPTB maybe you want to have a quick look at my latest changes, but the example notebooks looks fine so it should be fine I guess.