chore(TickDuration): Remove deprecated TickDuration and all associated symbols.

[schveiguy]

Finally, when you say to, you mean std.conv.to and never core.time.to!

[github-actions]

DMD perf check

Metric	Base	PR	Δ
compile hello.d (instr)	215.1 M	213.4 M	-0.781%
compile hello.d -O -release (instr)	233.4 M	231.7 M	-0.719%
compile Phobos codegen (instr)	1,472.4 M	1,475.5 M	+0.212%

Breakdown — compile hello.d

Phase (wall, self time)	Base	PR	Δ
parse	33.4 ms	31.8 ms	-4.88%
sema3	6.0 ms	5.7 ms	-5.00%
sema_other	13.6 ms	13.8 ms	+1.86%
codegen	1.9 ms	1.8 ms	-2.74%
sema1	10.0 ms	10.0 ms	-0.05%

All measurements

Metric	Base	PR	Δ
compile hello.d (instr)	215.1 M	213.4 M	-0.781%
compile hello.d -O -release (instr)	233.4 M	231.7 M	-0.719%
compile Phobos (instr)	5,120.7 M	5,122.1 M	+0.026%
compile Phobos codegen (instr)	1,472.4 M	1,475.5 M	+0.212%
compile vibe.d (instr)	15,113.4 M	15,109.8 M	-0.024%
dmd binary size (stripped)	6.86 MB	6.86 MB	0.00%
hello binary size (stripped)	0.72 MB	0.72 MB	0.00%
peak RSS (compile hello.d)	43.40 MB	43.07 MB	-0.77%
peak RSS (compile Phobos)	619.0 MB	617.2 MB	-0.29%
peak RSS (compile vibe.d)	1917 MB	1917 MB	-0.01%
compile dmd itself (wall)	12.0 s	12.0 s	+0.26%
compile hello.d (wall)	64.8 ms	63.1 ms	-2.68%
compile Phobos (wall)	1,577 ms	1,552 ms	-1.59%

_{e4a4eb3 vs merge-base 86b74e2 · about these metrics}