feat: implement bandwidth limit for proxy-cache

[zyyw]

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Comprehensive Summary of your change

Issue being fixed

Fixes #20589

Please indicate you've done the following:

• Well Written Title and Summary of the PR
• Label the PR as needed. "release-note/ignore-for-release, release-note/new-feature, release-note/update, release-note/enhancement, release-note/community, release-note/breaking-change, release-note/docs, release-note/infra, release-note/deprecation"
• Accepted the DCO. Commits without the DCO will delay acceptance.
• Made sure tests are passing and test coverage is added if needed.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed in website repository.

Testing

test case 1: proxy_speed_kb = "-1"

        "metadata": {
            "proxy_speed_kb": "-1",
            "public": "false",
            "retention_id": "1"
        },
        "name": "proxy1-unlimited1",

test case 2: proxy_speed_kb = "100"

        "metadata": {
            "proxy_speed_kb": "100",
            "public": "false",
            "retention_id": "2"
        },
        "name": "proxy2-limited-100kb",

100 is in kilo bit per second, 100/8 = 12.5 kilo bytes per second

test case 3: proxy_speed_kb = "300"

        "metadata": {
            "proxy_speed_kb": "300",
            "public": "false",
            "retention_id": "3"
        },
        "name": "proxy3-limited-300kb",

300 is in kilo bit per second, 300/8 = 37.5 kilo bytes per second

test case 4: proxy_speed_kb = "1024"

        "metadata": {
            "proxy_speed_kb": "1024",
            "public": "false",
            "retention_id": "4"
        },
        "name": "proxy4-limited-1024kb",

1024 is in kilo bit per second, 1024/8 = 128 kilo bytes per second

test case 5: proxy_speed_kb = "102400"

        "metadata": {
            "proxy_speed_kb": "102400",
            "public": "false",
            "retention_id": "5"
        },
        "name": "proxy5-limited-102400kb",

1024 is in kilo bit per second, 1024/8 = 12800 kilo bytes per second

[codecov]

Codecov Report

Attention: Patch coverage is 17.24138% with 48 lines in your changes missing coverage. Please review.

Project coverage is 66.28%. Comparing base (c8c11b4) to head (67df2c9).
Report is 252 commits behind head on main.

Files	Patch %	Lines
src/controller/proxy/remote.go	0.00%	12 Missing ⚠️
src/pkg/project/models/project.go	0.00%	10 Missing ⚠️
src/server/v2.0/handler/project.go	0.00%	10 Missing ⚠️
src/server/v2.0/handler/project_metadata.go	0.00%	6 Missing ⚠️
src/server/middleware/repoproxy/proxy.go	0.00%	5 Missing ⚠️
.../controller/replication/transfer/image/transfer.go	0.00%	2 Missing ⚠️
src/server/middleware/repoproxy/tag.go	0.00%	2 Missing ⚠️
src/controller/proxy/controller.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main   #20812       +/-   ##
===========================================
+ Coverage   45.36%   66.28%   +20.91%     
===========================================
  Files         244     1046      +802     
  Lines       13333   114043   +100710     
  Branches     2719     2845      +126     
===========================================
+ Hits         6049    75591    +69542     
- Misses       6983    34334    +27351     
- Partials      301     4118     +3817     

Flag	Coverage Δ
unittests	66.28% <17.24%> (+20.91%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/controller/proxy/options.go	100.00% <100.00%> (ø)
src/lib/iothrottler.go	0.00% <ø> (ø)
src/controller/proxy/controller.go	14.91% <0.00%> (ø)
.../controller/replication/transfer/image/transfer.go	33.76% <0.00%> (ø)
src/server/middleware/repoproxy/tag.go	0.00% <0.00%> (ø)
src/server/middleware/repoproxy/proxy.go	4.42% <0.00%> (ø)
src/server/v2.0/handler/project_metadata.go	0.00% <0.00%> (ø)
src/pkg/project/models/project.go	40.14% <0.00%> (ø)
src/server/v2.0/handler/project.go	5.15% <0.00%> (ø)
src/controller/proxy/remote.go	0.00% <0.00%> (ø)

... and 1278 files with indirect coverage changes

[wy65701436]

lgtm

[chlins]

lgtm