Add StreamReaderReadLineTests and base TextReaderReadLineTests

[nietras]

Follow up to #2083 cc: @adamsitnik feel free to make whatever changes you deem necessary. Note I expanded line length range to include 1025-2048 specifically to trigger StreamReader.ReadLine path that allocates StringBuilder.

[nietras]

Example output, with no difference in PR branch.

dotnet run -c Release -f net6.0 --filter *StreamReaderReadLine* --coreRun "C:\git\oss\runtime-m\artifacts\bin\testhost\net7.0-windows-Release-x64\shared\Microsoft.NETCore.App\7.0.0\CoreRun.exe" "C:\git\oss\runtime-pr\artifacts\bin\testhost\net7.0-windows-Release-x64\shared\Microsoft.NETCore.App\7.0.0\CoreRun.exe"

BenchmarkDotNet=v0.13.1.1620-nightly, OS=Windows 10.0.19044.1348 (21H2)
AMD Ryzen 9 5950X, 1 CPU, 32 logical and 16 physical cores
.NET SDK=7.0.100-alpha.1.21568.2
[Host] : .NET 6.0.0 (6.0.21.48005), X64 RyuJIT
Job-FHQAYY : .NET 7.0.0 (42.42.42.42424), X64 RyuJIT
Job-XIARQD : .NET 7.0.0 (42.42.42.42424), X64 RyuJIT
PowerPlanMode=00000000-0000-0000-0000-000000000000 Arguments=/p:DebugType=portable,-bl:benchmarkdotnet.binlog IterationTime=250.0000 ms MaxIterationCount=20 MinIterationCount=15 WarmupCount=1 

Method	Job	Toolchain	LineLengthRange	Mean	Error	StdDev	Median	Min	Max	Ratio	RatioSD	Gen 0	Gen 1	Allocated
ReadLine	Job-FHQAYY	m	[ 0, 0]	38.20 μs	0.079 μs	0.074 μs	38.17 μs	38.10 μs	38.34 μs	1.00	0.00	0.1528	-	3 KB
ReadLine	Job-XIARQD	pr	[ 0, 0]	38.18 μs	0.054 μs	0.051 μs	38.18 μs	38.11 μs	38.26 μs	1.00	0.00	0.1524	-	3 KB
ReadLineAsync	Job-FHQAYY	m	[ 0, 0]	154.39 μs	0.871 μs	0.815 μs	154.32 μs	153.22 μs	155.90 μs	1.00	0.00	34.9265	-	579 KB
ReadLineAsync	Job-XIARQD	pr	[ 0, 0]	156.00 μs	1.474 μs	1.306 μs	155.75 μs	153.04 μs	158.65 μs	1.01	0.01	35.2723	-	579 KB
ReadLine	Job-FHQAYY	m	[ 0, 1024]	11.39 μs	0.086 μs	0.081 μs	11.34 μs	11.29 μs	11.56 μs	1.00	0.00	3.7455	0.0451	61 KB
ReadLine	Job-XIARQD	pr	[ 0, 1024]	11.24 μs	0.027 μs	0.024 μs	11.23 μs	11.22 μs	11.28 μs	0.99	0.01	3.7057	0.0452	61 KB
ReadLineAsync	Job-FHQAYY	m	[ 0, 1024]	15.46 μs	0.472 μs	0.543 μs	15.64 μs	14.03 μs	16.09 μs	1.00	0.00	3.8828	0.0626	64 KB
ReadLineAsync	Job-XIARQD	pr	[ 0, 1024]	14.36 μs	0.755 μs	0.870 μs	14.15 μs	12.73 μs	15.95 μs	0.93	0.07	3.8654	0.0595	64 KB
ReadLine	Job-FHQAYY	m	[ 1, 1]	46.99 μs	0.203 μs	0.170 μs	46.94 μs	46.79 μs	47.33 μs	1.00	0.00	8.0706	-	133 KB
ReadLine	Job-XIARQD	pr	[ 1, 1]	46.76 μs	0.140 μs	0.131 μs	46.72 μs	46.60 μs	47.00 μs	1.00	0.00	8.0706	-	133 KB
ReadLineAsync	Job-FHQAYY	m	[ 1, 1]	129.58 μs	1.331 μs	1.245 μs	129.34 μs	127.84 μs	131.65 μs	1.00	0.00	31.2500	-	517 KB
ReadLineAsync	Job-XIARQD	pr	[ 1, 1]	128.40 μs	0.953 μs	0.892 μs	128.38 μs	126.73 μs	129.96 μs	0.99	0.01	31.5041	-	517 KB
ReadLine	Job-FHQAYY	m	[ 1, 8]	40.11 μs	0.704 μs	0.588 μs	40.35 μs	38.99 μs	41.15 μs	1.00	0.00	5.6533	-	95 KB
ReadLine	Job-XIARQD	pr	[ 1, 8]	41.61 μs	0.821 μs	0.843 μs	41.87 μs	39.66 μs	42.49 μs	1.04	0.02	5.6966	-	95 KB
ReadLineAsync	Job-FHQAYY	m	[ 1, 8]	87.17 μs	0.843 μs	0.748 μs	86.84 μs	86.54 μs	89.10 μs	1.00	0.00	17.6105	-	289 KB
ReadLineAsync	Job-XIARQD	pr	[ 1, 8]	89.34 μs	1.754 μs	1.950 μs	89.13 μs	86.42 μs	93.05 μs	1.03	0.02	17.4581	-	289 KB
ReadLine	Job-FHQAYY	m	[ 9, 32]	19.85 μs	0.151 μs	0.134 μs	19.85 μs	19.66 μs	20.13 μs	1.00	0.00	3.2731	-	54 KB
ReadLine	Job-XIARQD	pr	[ 9, 32]	19.72 μs	0.098 μs	0.092 μs	19.74 μs	19.49 μs	19.81 μs	0.99	0.01	3.2813	-	54 KB
ReadLineAsync	Job-FHQAYY	m	[ 9, 32]	33.40 μs	0.404 μs	0.378 μs	33.30 μs	32.91 μs	34.16 μs	1.00	0.00	6.4103	-	105 KB
ReadLineAsync	Job-XIARQD	pr	[ 9, 32]	33.50 μs	0.422 μs	0.394 μs	33.42 μs	32.85 μs	34.22 μs	1.00	0.02	6.3559	-	105 KB
ReadLine	Job-FHQAYY	m	[ 33, 128]	13.75 μs	0.058 μs	0.054 μs	13.74 μs	13.66 μs	13.86 μs	1.00	0.00	2.7316	-	45 KB
ReadLine	Job-XIARQD	pr	[ 33, 128]	13.75 μs	0.040 μs	0.037 μs	13.76 μs	13.68 μs	13.81 μs	1.00	0.00	2.6959	-	45 KB
ReadLineAsync	Job-FHQAYY	m	[ 33, 128]	20.75 μs	0.757 μs	0.871 μs	20.87 μs	19.53 μs	21.80 μs	1.00	0.00	3.5874	-	59 KB
ReadLineAsync	Job-XIARQD	pr	[ 33, 128]	20.47 μs	0.533 μs	0.613 μs	20.17 μs	19.57 μs	21.61 μs	0.99	0.04	3.5737	-	59 KB
ReadLine	Job-FHQAYY	m	[ 129, 1024]	14.13 μs	0.603 μs	0.695 μs	14.46 μs	12.14 μs	14.65 μs	1.00	0.00	3.7330	0.0566	61 KB
ReadLine	Job-XIARQD	pr	[ 129, 1024]	14.32 μs	0.599 μs	0.690 μs	14.57 μs	12.39 μs	14.89 μs	1.02	0.08	3.6999	0.0569	61 KB
ReadLineAsync	Job-FHQAYY	m	[ 129, 1024]	14.96 μs	0.589 μs	0.679 μs	15.24 μs	13.80 μs	15.89 μs	1.00	0.00	3.8411	0.0549	63 KB
ReadLineAsync	Job-XIARQD	pr	[ 129, 1024]	14.64 μs	0.720 μs	0.829 μs	13.99 μs	13.72 μs	15.79 μs	0.98	0.06	3.8117	0.0561	63 KB
ReadLine	Job-FHQAYY	m	[1025, 2048]	12.58 μs	0.158 μs	0.148 μs	12.56 μs	12.41 μs	12.93 μs	1.00	0.00	5.5177	0.1505	91 KB
ReadLine	Job-XIARQD	pr	[1025, 2048]	15.48 μs	0.794 μs	0.914 μs	15.79 μs	12.37 μs	16.09 μs	1.22	0.08	5.5268	0.1764	91 KB
ReadLineAsync	Job-FHQAYY	m	[1025, 2048]	13.30 μs	0.072 μs	0.067 μs	13.29 μs	13.22 μs	13.44 μs	1.00	0.00	5.5614	0.2119	91 KB
ReadLineAsync	Job-XIARQD	pr	[1025, 2048]	13.40 μs	0.139 μs	0.124 μs	13.38 μs	13.27 μs	13.71 μs	1.01	0.01	5.5946	0.2131	91 KB

[adamsitnik]

LGTM, thank you @nietras !