Add UI on brave://ipfs for tweaking Datastore.StorageMax

[lidel]

Brave v1.19 ships with StorageMax set to 1GB by default:

	"Datastore": {
		"GCPeriod": "1h",
		"StorageGCWatermark": 90,
		"StorageMax": "1GB"

I've been asked by multiple users how to increase this limit.

Right now they need to:

1. go to http://127.0.0.1:45001/webui → Settings OR find the config file on the disk
2. change the StorageMax value and save the config
3. restart the node to apply the config change

I suggest we improve this common operation by adding two UI on the brave://ipfs (or proposed brave://settings/ipfs) page:

• <input type="number" that defines the number of GB read from the config file
• "Apply" button that updates value in config + restarts the node.

cc @autonome @jessicaschilling @bbondy

[bbondy]

I think maybe in the chrome://settings page in its new section will be better, but ++ on the option.

[jessicaschilling]

Makes sense to me.

[stephendonner]

Verified PASSED using nightly build on macOS:

Brave	1.23.31 Chromium: 89.0.4389.86 (Official Build) nightly (x86_64)
Revision	0c2dac31bc21e806a791641316e99920f84ea52c-refs/branch-heads/4389@{#1472}
OS	macOS Version 11.2.3 (Build 20D91)

13720-steps.md

Maximum IPFS cache size (GB) value	StorageMax value
0	0
1	1000000000
9999	9999000000000
99999	99999000000000
99999999	99999990000000000
999999999	999999999000000000
9999999999	0

Verified:

• Maximum IPFS cache size (GB) input box only appears when Local node is set as the resolver in Method to resolve IPFS resources via brave://settings

• typically (there are instances which I am still investigating where it doesn't) when the user changes the value, it is soon reflected via brave://ipfs

• not able to input non-numeric characters

• Value must be greater than or equal to 1 tooltip appears in textbox, correctly, on hover over bad input

• up and down arrows increment and decrement input value by 1 each press, respectively

• the upper bounds for a non-zero StorageMax value is 9999999999

• leading characters such as 09 are accepted and not stripped, but reflect correctly in StorageMax, e.g. 9000000000 for 09