Use native token symbol and adjust transaction execution text

[iamacook]

What it solves

Resolves #3133

How this PR fixes it

• The native currency name should not appear within the Safe (unless semantically correct). The symbol is used in place: receive modal, transaction fees, review (new safe) step, native coin value in send modal, contract interaction review/review custom transaction, multisend details, transaction approval.
• "{{price}} (fee price) {{name}} in this wallet to fund this confirmation." should now be ""{{number}} {{symbol}} in this wallet to fund the associated transaction fee."
• "This action will execute this transaction. A separate Transaction will be performed to submit the execution." should now be "This action will execute the selected transaction."

[github-actions]

CLA Assistant Lite All Contributors have signed the CLA.

[coveralls]

Pull Request Test Coverage Report for Build 1553732318

• 0 of 2 (0.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 32.35%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/routes/safe/components/Transactions/TxList/MultiSendDetails.tsx	0	1	0.0%
src/routes/safe/components/Transactions/TxList/modals/ApproveTxModal.tsx	0	1	0.0%

Totals
Change from base Build 1550457710:	0.0%
Covered Lines:	3081
Relevant Lines:	8468

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💛 - Coveralls

[github-actions]

Deployment links

🟠 Safe Rinkeby	⚪ Safe Mainnet	🟣 Safe Polygon	🟡 Safe BSC	⚫ Safe Arbitrum	🟢 Safe xDai

[github-actions]

E2E Tests Failed
Check the results here: https://github.com/gnosis/safe-react-e2e-tests/actions/runs/1553768505

Failed tests:

• ❌ Add an existing safe Add an existing safe
• ❌ Address book Address book
• ❌ Safe Apps List Safe Apps List
• ❌ Read-only transaction creation and review Create and review a Send Funds transaction

[github-actions]

ESLint Summary View Full Report

Annotations are provided inline on the Files Changed tab. You can also see all annotations that were generated on the annotations page.

Type	Occurrences	Fixable
Errors	0	0
Warnings	0	0
Ignored	3	N/A

• Result: ✅ success
• Annotations: 0 total

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^{Report generated by eslint-plus-action}

[katspaugh]

Nice!

[katspaugh]

Tested on Rinkeby and Polygon, the symbol is displayed correctly.

Made a slight adjustment to make the symbol bold like the amount itself.